* refactoring assets management code
* finalizing refactoring of assets management
* various code review of new assets management code
* fix#2281
* fix#1961
* fix#1293
* fix#1275
* fix update scheduler timing logic
* forward compatibility (to be removed once 1.11+ is widespread)
* more codereview; give admins ability to specify own assets.json
* "assetKey" is more accurate than "path"
* fix group count update when building dom incrementally
* reorganize content (order, added URLs, etc.)
* ability to customize updater through advanced settings
* better spinner icon
... for the sake of portability.
When including vapi-common.js in an HTML file, then the body element there
will have a "dir" attribute filled with the current locale's direction
(ltr or rtl).
The following languages are considered right-to-left: ar, he, fa, ps, ur.
Everything else is left-to-right.
After the "dir" attribute is set, we can decide in CSS which elements
should have different styling for rtl languages (e.g., body[dir=rtl] #id).
Chrome has getManifest(), Safari doesn't have anything, Firefox has an
asynchronous API...
So, instead of using extension APIs, store the common informations
(extension name, version, homepage url) in a file (vapi-appinfo.js), which
can be included when it's needed (its data will be available at vAPI.app.____).
The file's content is updated each time the extension is being built, so
it shouldn't be modified manually.
