Hyperbole 7.0.7: TEST RELEASE - fixed new, more efficient htype symbol table lookups

BUTTONS

- Action Buttons: A new, universal syntax for creating implicit buttons
  that execute any existing action types or Elisp functions.  Such
  buttons are delimited by angle brackets, < >, and come in three types:
  action type invocations, function calls and variable displays.  See
  "(hyperbole)Action Buttons" for examples and details on this exciting
  new capability.

- Labeled Implicit Buttons: Optional <[labels]> that precede implicit
  buttons.  This enables implicit buttons to be activated by name when
  in the current buffer or anywhere when added to the global buttons
  file (personal button file).

- Link to Buttons: New implicit button types that link to buttons based
   on their categories and labels:

    In Buffer Syntax                                       Implicit Button Type
    ========================================================================
    <elink: explicit button label to link to: optional ebut file>  link-to-ebut
    <glink: global button label to link to>                        link-to-gbut
    <ilink: implicit button label to link to: optional ibut file>  link-to-ibut

- Other New Implicit Button Types:
    debugger-source: Jump to the source of errors from the Python pytype package
    ipython-stack-frame: Jump to the source of ipython stack traces and exceptions

- Much Faster Implicit Buttons: Major speedup in implicit button identification
  and activation even with the new generalized Action implicit button type
  syntax, due to internal optimizations.

- Pathname Flashing: Pathname implicit buttons now flash when activated.

- Pathname References: Pathname implicit buttons may contain both link anchors
  and line and column numbers.  Format is:
    "<path>[#<link-anchor>]:<line-num>[:<col-num>]"

- Shell Script Link Anchors: Link anchors now work for shell script editing modes
  as well using comment lines as the anchors, e.g. "myscript.sh#Env Variables".

- Dir Variable Separators: Variables in paths no longer require a trailing directory
  separator.  Both of these are live Hyperbole paths:
  "${hyperb:dir}DEMO#Smart Mouse Keys"
  "${hyperb:dir}/DEMO#Smart Mouse Keys"

DOCUMENTATION

- DEMO: New sections on Button Files and Global Buttons.

- Action Types: link-to-gbut, link-to-ibut - Added.

- hpath:native-image-suffixes: documented this setting for controlling
  image types that Hyperbole displays within Emacs.

- Implicit Button Types: Split off type descriptions to this new
  subsection and added these types: ripgrep-msg, ipython-stack-frame,
  ilink (link to implicit button), glink (link to global button), and
  elink (link to explicit button).

- DEMO (Action Buttons): Added description and examples.

- Hyperbole Manual, DEMO (Implicit Buttons): Added description and
  example of implicit button labels.

- Glossary: Updated Implicit Button and Global Button entries with
  changes.

KOUTLINER

- When 'c' (clip to lines per cell) is omitted from a viewspec, clipping
  now changes to whatever the default number of lines per cell is
  (typically, unlimited).  The same goes for the 'l' spec (limit display
  to a certain level of cells).

MENUS

- Pulldown Menus:   Implicit-Button/Label: Added to add a label.
                    Implicit-Button/Rename - Added to rename the label
                    of an implicit button.

- Minibuffer Menus: hui-mini.el (hui:menus): Added Ibut/Label and
  Ibut/Rename.

ORG MODE

- Radio Targets and Links: Smart Keys now handle these.

- Links: Smart Keys handle both internal and external Org mode links.

PROGRAMMING

- ibut:at-type-p: Added to test if point is on a specific type of
  implicit button.

- hypb:region-with-text-property-value: Added and used in hysy-org.el.

- hsys-org-mode-function, hsys-org-mode-p: Added to determine when
  hsys-org actions are activated.

- ebut:key-src-set-buffer, hbut:key-src-set-buffer, hbut:key-list,
  hbut:ebut-key-list, hbut:ibut-key-list, hbut:label-list): Added
  to allow selection of labeled Hyperbole buttons in currrent buffer by
  name.

- gbut:get, hbut:map, ibut:label-map, ibut:key-src, ibut:key-to-label,
  ibut:label-to-key, hui:ebut-act, ibut:summarize, ibut:label-start,
  ibut:label-end, ibut:label-p, ibut:get, hui:ibut-label-create,
  hui:ibut-rename, hui:ibut-message, ibut:alist, ibut:list, ibut:map,
  ibut:next-occurrence, ibut:label-regexp, gbut:ibut-key-list, ebut:to,
  gbut:to, ibut:to, ibut:label-separator, hbut:label-regexp,
  ibut:rename, hbut:get: Added to support implicit button labels and
  links to buttons.
  hbut:label-p: Updated to handle implicit button labels.
  ibut:label-separator-regexp, hbut:outside-comment-p: Added.

- elink, elink:start, elink:end: Added for in-buffer links to explicit buttons.
  glink, glink:start, glink:end: Added for in-buffer links to global buttons.
  ilink, ilink:start, ilink:end: Added for in-buffer links to implicit buttons.

- hsys-org-set-ibut-label: Added and used in org-mode ibtype.
  org-mode, hsys-org-at-block-start-p: Added Action Key activation of
  Org blocks when on 1st line of def.

SMART (ACTION AND ASSIST) KEYS

- hpath:find-program: Changed to prioritize hpath:native-image-suffixes
  over hpath:internal-display-alist over hpath:external-display-alist-macos
  instead of the reverse.  This prevents external viewers from being
  used when internal viewers are also in effect.