Adding workspace scheme based project helper (#292)

* Added workspace based target build settings lookup
* Store project/ws path in the build target cache as well, to ensure consistency
* Added an IsDebug mode for projecthelper, which looks up both workspace and project based build settings; and falls back to the project based ones if they do not match.
* Added new exported functions for projectmanager ReadSchemeBuildSettingString and IsMainTargetProductTypeAppClip
* New input buildAction for projectmanager, used to look up matching target for Scheme
* Some cleanup around project parsing

Author: lpusok