refactor(menu): cleaned up menu

[johannehouweling]

Fixes #339
Fixes #338
Fixes #340
Fixes #343
Fixes #345

Also adds caching to speed up external data decencies by more than factor 10.

Cleaned up the menu a lot:

Cleaner Search

Paging for Tools, automatic parsing of tools from ...service.json, addresses #338

Full visibility for methods:

Restored balance of mobile, addresses #339

by shifting Search into off-canvas on mobile and cleaned up dropdown menus on off-canvas:

Now also includes methods in search (methods and tools are pulled directly from methods_index.json and service_index.json, no longer hardcoded, addresses #340

[johannehouweling]

Now also includes methods in search (methods and tools are pulled directly from methods_index.json and service_index.json, no longer hardcoded, addresses #340

See above

[johannehouweling]

Removed toplevel location from search to address #345.

[johannehouweling]

@ozancinar, @egonw I added caching to Flask, to cache external interactions (loading of "service_index.json" and querying Zenodo and BioStudies) which are slow moving data repos.

comes with a new dependency flask-caching, which I added to requirements.txt

Caching now for 5days. Makes sense to review if other locations can make use of this. Tried to refactor aleady, but still might be some locations left that do a request directly to the .json. But the longest time are the Zenodo and BioStudy API calls which are now entirely cached. For the data tab this reduces loading times by a magnitude from ~2s to 0.2s (locally).

w/o chache

w cache on second reload

[johannehouweling]

Rebased this branch to make mergeable.