Ideally, we want to pass shortcut keys to the component to handle, and
only fall back to invoking a menu item if the component was unable to
handle the keyboard event, or if the action was triggered by
clicking/selecting an item in the menu itself. The old implementation
tried to work out whether the action was triggered by a shortcut by
checking the event's characters and modifiers. This method was
inaccurate, because some shortcuts (such as arrow keys) may add
unexpected numpad/function modifier flags.

We now try handling shortcut keys directly in the peer, and pass events
up to the superclass (which will forward them to the main menu) if the
event could not be handled.

This commit also adjusts some Objective-C method signatures to use the
correct string encoding for the BOOL type.

This commit reverts part of f73f8ee84 which introduced an issue when
resizing a subcomponent with an attached OpenGLContext.

More details of the issue can be seen at
https://github.com/juce-framework/JUCE/issues/914.

See BREAKING-CHANGES.txt for more details.

This fixes warnings that are emitted when building with the `-analyze`
flag enabled.

Previously, the following plugins were causing issues when hosting their
editors:

- Softube plugins. I used Saturation Knob for testing, which crashed when
  deleting the temporary parent view.
- KORG Gadget series, which displayed a black screen after the temporary parent
  view was deleted.
- FabFilter Pro-C, which displayed at the wrong scale when opened on a
  retina display.

The default main JuceActivity for JUCE apps calls appNewIntent() in its onNewIntent() implementation which is defined in juce_gui_extra. This commit moves the implementation into juce_gui_basics.

Also added support for selectAll: selector forwarding in NSViewComponentPeer