As pointed out in a comment on T89421, if a MTL file contained something like: map_Ka -o 1 2.png then it was parsed as having offset 1 2 and the texture filename just a .png. Make it so that mtl option numbers are parsed in a way where the number is only accepted only if it's followed by whitespace.
Extend unit test coverage, which also needs to apply this diff to the subversion tests repository:
--- io_tests/obj/materials.mtl (revision 62967) +++ io_tests/obj/materials.mtl (working copy) @@ -57,7 +57,7 @@ newmtl Parser_ScaleOffset_Test map_Kd -o 2.5 OffsetOneValue.png map_Ks -s 1.5 2.5 -o 3.5 4.5 ScaleOffsetBothTwovalues.png -map_Ns -s 0.5 ScaleOneValue.png +map_Ns -s 0.5 1.Value.png # these mtl options are not supported yet map_Ka -s 1.5 2.5 3.5 -o 4.5 5.5 6.5 -mm 0.1 0.2 sometex_a.jpg