Use local event monitor for key equivalent view

This ensures we get all key events, for example in the bundle item chooser window the pop-up button’s menu would previously see the key down event before the key equivalent view, so enabling recording and pressing ⌘1-3 would not record that key equivalent, but instead activate the corresponding (pop-up) menu item.
Use NSTextInputContext instead of NSInputManager

The latter has been deprecated since 10.6 but hasn’t given any deprecation warnings (and it’s not like I’m eager to touch the NSTextInput protocol implementation, as I just barely understand how this stuff is supposed to work).
Look for process id file from 2.0-alpha.9553 and earlier

This is only when updating from an earlier version: Previously we would not find the pid file from the old instance and thus not tell it to quit.
Avoid clash with NSCell’s keyEquivalent property

The rationale for the ‘string’ suffix is that our properties are things to be displayed rather than behavioral properties.
Move highlight_ranges.h to ui subfolder

Only sources in the ui folder use this code and was previously including it from a parent folder, which breaks the hierarchical ordering of sources: you can include child folders, not ancestors.