Add support for "git describe" based version numbers.

Also, move cpack related code into its own module, to clean up the main CMakeLists.txt
Add guessed paths for Win8 and Win81 SDK to DirectX search paths
Clean up the previous commit a bit

The was_removed variable was rather unnecessary
Oh and while we're at it I suppose another fix
And cover the one in scene_destroy
Fix another bug (don't commit without compiling)

Also don't code in anger
Merge pull request #35 from BtbN/master

git describe based version number support for CPack
Improve ALL_BUILD.vcxproj.user copy check
Merge pull request #37 from BtbN/master

Improve ALL_BUILD.vcxproj.user copy check
Add module UI export capability

Add the ability to be able to call and use toolkit-specific or
program-specific user interface in modules.

User interface code can be either bundled with the module, or 'split'
out in to separate libraries (recommended).

There are three reasons why splitting is recommended:

  1.) It allows plugins to be able to create custom user interface for
      each toolkit if desired.

  2.) Often, UI will be programmed in one language (the language of the
      toolkit), and core logic may be programmed in another.  This
      allows plugins to keep the languages separated if necessary.

  3.) It prevents direct linkage of UI toolkits libraries with core
      module logic.

Splitting is not required, though is recommended if you want your plugin
to be more flexible with other user interface toolkits or programs.

Will implement a generic properties lookup next, which will be used for
automatic UI handling so that plugin UI isn't necessarily required.
Make some minor adjustments to module UI code

Made it so that enum_ui returns a const pointer to a structure rather
than require an actual structure.

Changed a few of the descriptions that I missed.
Don't rely on static data

The ui_enum function gets a const struct obs_ui_info **, which basically
means it expects static data to be used.  I originally had it the other
way around, but yea, it's probably not a good idea, so I'm going to
revert back to the original code instead, which doesn't rely on the data
being static.
Add support for modeless UI creation

I realized that I had intended modeless UI to be usable by plugins, but
it had been pointed out to me that modeless really needs to return a
pointer/handle to the user interface object that was created.
Simplify/improve UI exporting a bit more

Reduce and simplify the UI export interface.  Having to export functions
with designated names was a bit silly for this case, it makes more sense
for inputs/outputs/etc because they have more functions associated with
them, but in this case the callback can be retrieved simply through the
enumeration exports.  Makes it a bit easier and a little less awkward
for this situation.

Also, changed the exports and names to be a bit more consistent,
labelling them both as either "modal" or "modeless", and changed the UI
function calls to obs_exec_ui and obs_create_ui to imply modal/modeless
functionality a bit more.
Implement properties definition interface

Implement a properties definition interface to allow modules to export
general properties associated with objects of libobs.

The properties definition interface allows the option for automatic
settings UI generation (which will make simple plugins easier to develop
without the need for user interface), as well as allow real-time
property editing of values of things like sources/outputs/etc without
having to open property dialogs.  More property types can be added in
the future as needed as well.
Add property list callbacks

- Add property list callbacks to sources/outputs/encoders so that if
  necessary user interface can be automatically generated or perhaps a
  property list widget can be used for them.

- Change some of the property API names.  obs_property_list_t felt a bit
  awkward when actually using it, so I just renamed it to
  obs_properties_t.

- Removed the getdata/setdata nad getparam/setparam functions from
  sources/services, they will be superseded by the dynamic procedure
  call API.
Improve thread safety in UI code

- Implemented better C++ classes for handling scenes/sources/items in
  obs.hpp, allowing them to automatically increment and decrement the
  references of each, as well as assign them to QVariants.

- Because QVariants are now using the C++ classes, remove the pointer
  QVariant wrapper.

- Use the new C++ classes with the QVariant user data of list box items,
  both for the sake of thread safety and to ensure that the data
  referenced is not freed until removed.  NOTE: still might need some
  testing.

- Implemented a source-remove signal from libobs, and start using that
  signal instead of the source-destroy signal for signalling item
  removal.
Remove header from obs/CMakeLists.txt
Fix copy&paste error
Move CPack win32 generator from NSIS to WIX