Added Squirrel Script source and includes........

In order to add them, add the includes through the object properties on
the game's DLL file.  They will be added as external dependencies.
Then, add a new filter in the engine/source part and call it squirrel.
Next, add a new filter inside of the squirrel folder in order to have a
src folder.  Add the files from the src folder into the new filter.
Compile and it should compile fine, however use at your own risk, as I
can not guarentee that will work yet (may have forgotten to tell ya guys
a step)