Fixes #310

Prevent long handle stretching user menu (adds ellipsis).
Remove handle when avatar is present, but keep handle when no avatar.

Add theme option to use Google Fonts.

Closes #193.

Sidebar now toggled based on media queries only.

Fixes #190

Closes #189

Inconsistency between media queries and qa_is_mobile_probably()

Shrink user avatar height and prevent overlapping (fixes #170).
Add hidden and flagged styles (fixes #168).
Add label to Login icon.
Move a function back into qa-theme.php.

From PRs by @pupi1985 (unmergeable due to file structure changes).
Closes #69.
Closes #126.

Fixes #114

Reduce unnecessary nesting

Line up h1 and search box.
Reduce nesting of search classes.