Fixed a bug caused by a missing temporary when swapping two
matrices. This could produce undefined results in the case where
both display inversion and the greyscale daltonizer were enabled
simultaneously.
Tightened up the code a little to make this kind of error
less likely by removing redundant state.
Removed the native prefix on some methods since they are not
native at all.
Change-Id: I716ffc8fbe76a304c60d45870074340c0121059f
8864415e2a