Bug 530443: Add support for "info sources" MI equivalent

*Implementation of -file-list-exec-source-files MI command.
*Add new Debug Sources view with tree-like structure

Change-Id: I6e734799712c059c8e53aa882777dfebd85aa0d5
Also-by: Jonah Graham <jonah@kichwacoders.com>
Signed-off-by: Baha El Kassaby <baha.elkassaby@gmail.com>
38 files changed