Caching of retrieved properties for EnvironmentVariablesFrm

+ fixed S_FALSE -> E_FAIL in the OnAfterOpenSolution and destroying _configFrm with Dispose of package
Major fixes with the MSBuildParser

* IEnumerable<EnvDTE.Project> DTEProjects for problems with the ProjectCollection.GlobalProjectCollection - see #8
* _getSolutionGlobalProperty() for work with the Solution-context on default projects
* getProject() now works with DTE and loads the Build.Evaluation.Project if needed
** when manually loading(if bug exist with LoadedProjects) we can use the _getGlobalProperties for problem #7
Ignore all actions if the build failed - Issue #9

ISolutionEvent <- +buildFailedIgnore
Merge branch 'develop'
public release

* NEW: Option for ignoring POST actions if the build failed.
* CHANGED: Major changes & fixes with the MSBuildParser.
* CHANGED: Improve work performance with the properties of projects