1036 local

Updated version of https://github.com/github/linguist/pull/1036
https://github.com/github/linguist/issues/1054 - This proved that .C should not be a C++ extension (it really really isn't) but that also the proper fix involves either listing all C and C++ extensions twice for projects that are using DOS style upper-case file names, or making these case insensitive somehow and removing .C and .H completely as they are only (so far as any sane C, C++ or Obj-C compiler is concerned) DOS style versions of their lower-case selves.