Unit tests for DISCL-218 - Serialize and restore sessions.

Also added min and max limits to window dimensions. This prevents oversized
windows from crashing the application (seen with PDFs), or too small windows
from being unreachable.

Change-Id: I296e0dd5f2bb2f294642195f5c9ac1418db3e63a
Merge pull request #121 from rdumusc/DISCL218

Unit tests for DISCL-218 - Serialize and restore sessions.