Revision 1933

* Thuban/Model/resource.py (get_system_proj_file): Add a filename
parameter so that this function can be used for all proj files in
Resource/Projections
(DEFAULT_PROJ_FILE, EPSG_PROJ_FILE): New. Predefined filenames for
get_system_proj_file

* Thuban/UI/projdialog.py (ProjFrame.__init__): Instead of one
ProjFile self.__sysProjFile use a dictionary of system ProjFile
objects self._sys_proj_files
(ProjFrame.build_dialog): Adapt to the new changes in the
ProjectionList constructor. Add a check button to toggle whether
EPSG projections are shown
(ProjFrame._OnShowEPSG): New. Handler for the epsg check button
events.
(ProjFrame.load_user_proj, ProjFrame.load_system_proj): Only show
the busy cursor if the files have not yet been loaded by the
dialog.
(ProjFrame.load_system_proj): Add a parameter for the name of the
proj file. Maintain the dictionary of system projections
self._sys_proj_files

* Thuban/UI/projlist.py (ProjectionList): Merge the system_projs,
user_projs parameters into one parameter proj_files which is a
list of proj files.
(ProjectionList._subscribe_proj_files)
(ProjectionList._unsubscribe_proj_files): New. Move
subscription/unsubscription of projfile messages to separate
methods
(ProjectionList.Destroy): The unsubscribe is now done in
_unsubscribe_proj_files
(ProjectionList.update_projections): We now have a list of proj
file objects
(ProjectionList.SetProjFiles): New method to set a new list of
proj file objects

* test/test_proj.py (ProjFileReadTests.test_get_system_proj_file):
Specify explicitly which system proj file to load.