Editor: Move LastBuildConfiguration to user data configuration file

Moved LastBuildConfiguration to a new class to house workspace settings
(potentially things like which windows were open). Editor ignores
workspace settings if the section isn't found. Bumped the user data
format version to 3.4.0.1.
Merge pull request #204 from gurok/340_separate_lastbuildconfig

Editor: Move LastBuildConfiguration to user data configuration file