Improve strings in configuration

[wengxt]

Summary

The terminology has been very inconsistent across different engines, some were trying to be kept same as the original port, some were just randomly using different terminology.

We should try to converge into a consistent list of terminology.

There's some significant issues like:

1. "page size" "number of candidates" are describing same thing
2. Too much details for a configuration option
3. boolean option should not include "whether"
4. integer option may need a better way to display "Unit".

[eagleoflqj]

5. Arrows (-> and <->) are ugly

[wengxt]

Global config:

some places that use "default" are actually "fallback".
some trigger/switch should be toggle
Xkb -> XKB

page size or whatever relevant options to be unified as "Candidates Per Page".

[wengxt]

Sub config that launches a page:

Configure "ABCD", instead of just "ABCD"

[Popolon]

• There are some inconsistency in names between uppercase/lowercase
• Some inconsistency between "X addon for fcitx5" and "X for fcitx5".
• "Number of x" at least sometimes means "The number of"/"number of the", not quantity, and could be not clear enough in current state.
• In configuration GUI tool, "Global options" tab some elements are not detailed enough, general terms are used without. As examples:
  • In "behavior" section, what could mean "Active By Default" (nothing indicate that's the (advanced) IM, like pinyin/anthy etc.
  • What means In this window "Enable input method" (with an input method by default) and "Disable input method" (with another input method by default)
• More generally precision about their categories or goal, maybe need a popup with some help .