use upper-case key names to represent shiftKey in <([acm]-)?.*> key mappings

[gdh1995]

This is another solution to #2388, and allows users to make such key mappings:

# press "Space"
map <space> scrollDown
# press "Shift+Space"
map <SPACE> scrollUp

# just treated as "<space>"
map <Space> scrollDown

The added logic is that if a keyChar (background_scripts/commands.coffee#L75) has only upper-case chars, then it means Shift should be pressed.

This does not influence most old mappings like <Left>, but will treat <f1> and <F1> differently.

[smblott-github]

Treating <f1> and <F1> differently would be problematic, would it not, since a fair few users will already have mappings for <F1>, which do not require the Shift key?

Is #2388 not more vim like too?

[gdh1995]

But the difference between <a> and <A> is just the shiftKey, and Vimium does not accept <s-a>.

I have no good idea about <F1>. Maybe we can add a function in runtime.onInstalled to detect old mappings and convert them?

[lydell]

Shameless plug: You could also use https://github.com/lydell/vim-like-key-notation for inspiration (which is used by VimFx).

[gdh1995]

I'm giving up this idea, because now I find that, usually a key like Alt+Shift+C should not be influenced by the Caps Lock key...