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