Latest changes from recent release versions of DAME

Mainly added Tools->Options to allow restrictions on what end user can
edit as well as to allow more data to go in .dsf files instead of .dam
files a well as the ability to add layer and group templates:
- Duplicated sprite entries now copy all relevant data.
- Fix bug where loading a file with layer templates added duplicate
entries.
- Added more options to control what can go in the settings file.
- Save sprites separately option has been moved to the Tools->Options
window.
- Prevent the map height options from showing up on new map layers.
- Options will be reset upon loading a project saved before versions
3.1.0 and 3.1.1
- Can now add layer group templates.

DAME 3.1.0
- Added layer templates (for maps only).
- Added options in Tools->Options to impose restrictions on what can be
done in a project (editing sprites/tilesets/only allow adding maps from
templates...)
- Added option to enable frame editing of sprites (enabled by default as
this was a pre-existing behaviour).
- Added option in sprites to lock rotation to 90 degree angles.
- Fix bug where links could be generated from an object to itself.
- Updated License for open source.
- Added some extra info to documentation.

See versionHistory file for mo