Add the ':char' syntax for defining character keys with a different
symbol.
This new kind of keys is used to implement Ctrl combinations in the
Serbian Cyrillic layout without showing latin letters while the Ctrl
modifier is activated.
This allows to add new kinds of keys that need more data without making
KeyValue's footprint bigger for common keys.
This changes the [_symbol] field into [_payload], which holds the same
as the previous field for more common keys but can hold bigger objects
for keys of the new "Complex" kind.
This also adds a complex key: String keys with a symbol different than
the outputted string.
Unit tests are added as the Java language is not helpful in making
robust code.
Put new example in Examples section; put all overview material at start; use "modmap" for the modmap tag but "mapping" for the various subtags; set out each subtag separately; stop illustrating example mappings as complete modmap.
* Post-edit on Metadata
① Tell reader exactly what to type to disable locale_extra_keys, as with prev. bullet
② Values should be quoted
③ Rephrase one passive
* locale_extra_keys obviates 2nd example under modmap
* Modmap: Where to put it; cancelling built-in mods (#665)
* Correct per Julow: not only Euro layouts
* Post-edit: Doesn't depend on "built-in" layout
* P-vs-L: Change "That is to say", sentence is not a restatement
* Discussion with Julow: Swipe graphic to HTML; at most one modmap
* Swipes: Center tables
This adds the new 'anticircle' attribute to layouts '<key>' elements
that configure the key to send when doing a anti-clockwise circle
gesture on it.
Labels are drawn the same way as indication.
Updated docs.
