preliminary keyboard shortcuts
a few more shortcuts
night theme shortcut
night mode settings saved
another bunch of keyboard shortcuts + iframe event fix (backported from release/0.13)
keyboard event hack to support WebKit buggy createEvent / initEvent objects
left/right arrows now using keymaster as well, for consistency
Merge remote-tracking branch 'origin/release/0.13' into feature/keyboard

Conflicts:
	lib/EpubReader.js
Merge remote-tracking branch 'origin/develop' into feature/keyboard
centralised keyboard shortcut management, abstract interface for keymaster
all keys configured
toggle keyboard shortcut for advanced MO options
fixed hide-ui display in library mode, changed shortcuts to pure-single-keys (no need for modifiers, in fact it interferes with screen readers), fixed alternative shortcuts by not combining them (memory leak in unbind())
code organisation
book library now keyboard-navigable + focus management when modal dialog is dismissed
iframe focusing when click activate from TOC
close buttons more meaningfull (accessible descriptions)
hide-ui toolbar display when tab-navigating
build + submodule
added keyboard shortcuts to control labels