Create CESyntaxExtensionErrorSheetController class and nib for it (ref #53)
Use tableView in syntax extension error sheet to improve aesthetic design

見栄えを良くして見やすくした。
Rename SyntaxManager.xib to SyntaxEditSheet.xib
Hide private IBActions
Tweak syntax extension error sheet
Merge branch 'refs/heads/refactor/extentionErrorSheet' into develop