TODO

1) Make various routines more efficient
2) Make write routines sort icons in descending size order
3) Add routines to stream-read an icns: (rather then entire glob as now)
   a) Add routine to determine sizes of icns in file
   b) Add routine to read a single icns from a file
3) Update API documentation, in txt and html format
4) Clarify in API the input/output for the various image functions
5) Remove usage of global variable to allow thread-safe usage of library