Delay firing menu command until the menu is closed

Otherwise menu close animation is totally lost when UI thread is hogged.
Side menu tweaks

Task #3178
Allow font to be set in TextAppearance for custom font widgets
Show current feed name in bold text

Harder than it seems, had to change callback listener to base class
FragmentAcitivtyWithMenu and also have App be the one to hold the
"current feed" property.
Get media type from MediaContent class
Fixed flashing images

Bug #3165