Add support for gthreads.
mtpc.h: Will be the main header file.
Add functions to manipulate device_table.

These changes add functions to allot/free the mtp_device_info and
device_table structures.
devicelist.[hc]: Cleanup device list treeview.

Cleans up functions to enable updates in a thread and add support
for popup menu to display "Device Properties".
Add thread support so that ui doesn't freeze when updating devices.

This commit should actually be merged with 5e901b79d6425bb94147cf809fc607c2e3474676
Update sidebar list update methods.