Makefile changes for version checks.
DeviceFolderTree implementation and signal handlers.

MtpcDeviceFolderTree handles and propogates open/load/popup. This class is
more or less complete.
Need to merget the MtpcDeviceFolderTree & MtpcHomeFolderTree into one class
and the object's signal handlers should do the bulk of the work.
Expose the enum for entry type on MtpcDevicelist class.
Add a wrapper for g_free.
Move Device memory handling to MtpcWindow.

This is a lot cleaner.
A few  things that still need to be done:
* management of the storage per device.
* lookup tables (hash tables) for devices and storage.
* storing path per storage (when devices are switched).
Debug logs for mtpc-device calls.