AUs are more likely to have 16 channels on a bus now that the 9.1.6
Atmos layout is available.

In some cases, processing key inputs may cause the currently-focused
text input target to be destroyed. If this happens, we shouldn't attempt
to reset the underlining on the target. We now reset the underlining
before processing key presses.

On some platforms, the superclass implementation can throw if it detects
that the preset data is malformed, but it's not clear exactly how the
system determines this.

We now apply only the JUCE state.

Rename look-and-feel method and update docs

- A repaint will always occur from a lookAndFeelChanged

- Created a new detail namespace
- Moved shared module implementation details into the detail namespace
- Split dependencies so source files only rely on details in the detail namespace
- Removed all code from the juce_gui_basics.cpp file

Fixes a bug on Windows when opening a FileChooser with the following
arguments.

    FileChooser ("",
                 "C:\path\to\file", // filename 'file' doesn't contain '.'
                 "",                // all extensions are allowed
                 true);

The expected behaviour is that the initially-displayed filename is
"file".

The actual behaviour was that the initially-displayed filename was
"file.file".

In order to display a WebKit based webview a plugin will deploy a
temporary standalone executable on the system and host the WebKit
instance inside that.

Until this commit it was possible that the message thread got stuck
waiting for the WebBrowserComponent's thread to finish, while the thread
was waiting for the message thread to handle a posted message.

Android devices won't necessarily be able to load MP3 files, so that
option has been removed from the file chooser. FLAC files should be
supported, but were missing from the MIME table.

The demo no longer tries to load files into the thumbnail view if they
previously failed to load into the transport.

On these platforms, calling flushBuffer from multiple threads
simultaneously will lead to deadlocks.