Added Android support

Kryvos could already build for Android, but like many desktop
application ports to mobile, it didn't look very good. This is an
attempt at fixing that. Now there is a new MainWindow class that
contains the common features used in a desktop application and mobile
application. The new classes DesktopMainWindow and AndroidMainWindow now
inherit from it, and perform their respective platform-specific
modifications to the GUI. The main thing that looked bad on Android was
button sizes and a few borders that don't make sense on a mobile device.
Most of the colors and font details are specified in Qt stylesheets, so
a new stylesheet was added to address this problem. The font-size of
text labels and buttons was adjusted to resize the app to a more usable
state on Android. Other widget classes were updated to add access
functionality for resizing purposes. I originally was going to create an
inheritance hierarchy for them, but decided the changes were applicable
to any custom platform-specific size adjustments. Finally, touch
scrolling was added to the file list and message text edits. I disabled
overshoot because overshoot makes scrolling on small widgets difficult.
Android manifest

A custom Android manifest file was generated with Qt Creator for setting
application name and icon in the final generated .apk release. Resource
files were also generated from the manifest file creation, which are the
icons used for the application.
Removed custom sizeHint from Delegate class

The Delegate class had a custom sizeHint, but it wasn't doing anything
useful. It was likely added previously for test purposes and forgotten.