Fixed purple bullets for wac_hc_hebullet.

GMod 13 broke this a tiny bit, so I fixed it up, nothing major but
useful none-the-less.
Merge pull request #48 from MattJeanes/bullet-fix

Fixed purple bullets for wac_hc_hebullet.
added support for different rotor angles (does not affect thrust direction)
broke everything but the viper and black hawk
Merge remote-tracking branch 'upstream/master'