Won't read any GIF under Windows

[Kevin Routley]

Just getting started but so far this project is looking fantastic!!

A blocker for Windows users: in Fl_Anim_GIF_Image.cxx, in the function readin, the following line (at or about line 548):

  FILE *gif = fopen(name_, "r");

needs to be changed to:

  FILE *gif = fopen(name_, "rb");

Without the binary flag, Windows will stop reading at the first zero byte.

[wcout]

Thank you very much for the report.