Add editorconfig-core-c library as submodule

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
TortoiseGitMerge: Add CEditorConfigWrapper class which calls editorconfig

Based on TortoiseSVN revision 25633

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Use EditorConfig tabwidth and indentstyle settings and show in ribbon status bar

Based on TortoiseSVN revision 25634-25636

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>