Initialize m_hTexture early.
Initialize m_hTexture early.

Doesn't really matter, but this way any code we add in the
constructor can't accidently use the pre-initialized value, which
is a nice guarantee when you're tracking down invalid texture IDs.

git-svn-id: 83c4c97093aeea62ac982fbfd516bf9db27f5c99@1309 c36c8488-0289-0348-9b64-b301f74bd9a7

BlueBrain/Tuvok,BlueBrain/Tuvok,BlueBrain/Tuvok