Handle sub issues better when batch running.
[Refactoring] Fix concurrent modification problem in IssueGroup.
[Refactoring] Fix in-editor batch fixing of sub issues.
[Refactorion] Don't parse files multiple times when batch fixing issues.
[Refactoring] Fix some analysis warnings/suggestions.
Merge branch 'master' into analysis-improvements
Merge branch 'master' into analysis-improvements

Conflicts:
	main/src/addins/MonoDevelop.Refactoring/MonoDevelop.CodeIssues/BatchFixer.cs
[Refactoring] Handle IssueProviders that declare an action provider.
Merge pull request #389 from mono-soc-2013/simonl/analysis-improvements

More analysis improvements