widgets: cleanup spacing

This file originally used a leading two-space indent in the class
factories to avoid getting too nested.  Use consistent four-space
indents.. for consistency.  It's not *that* nested.

Signed-off-by: David Aguilar <davvid@gmail.com>
widgets: preserve the maximized state

Remember whether git-cola has been maximized and restore the maximized
state at started.

Closes #172

Reported-by: Petter Strandmark <petter@maths.lth.se>
Signed-off-by: David Aguilar <davvid@gmail.com>