Partial update for the developer documentation, expanding aread of
design decisions, workflow and testing.
Updated the BuildEnv documentation.
Removed documentation referring to old pyffi dependency which is now
included as a sub-module.
Removed reference to bpy api generation as it nolonger works and the
repo that was referred to has been deleted.
Added instructions for pulling submodules and possible errors
encountered.
Grammer tidy up.
Standardised the SingleNif template methods, b_create_objects() ->
b_create_data()
Made the documentation more understandable.
Removed unnecessary title.
Fixed document generation errors, also redid commits which were lost
during the rebase process.
Merge pull request #97 from neomonkeus/doc/test_workflow

Documentation : Developer workflow & Test Framework