Known bugs in v0.9 ("-" = pending; "+" = fixed):
================================================

+ Unary plus in formula results in syntax error.

+ Values for environment.g,b,a are set incorrectly in gray images.

+ Loading of Filter Factory Library files would stop when the
  library filter count is reached, thus leaving additional
  filters unread (can be regarded as a feature though).
  -=< FFL is not directly supported in User Filter anymore >=-

+ Non-ASCII characters (found in some FFL library; maybe some kind
  of tabulator) result in functions failing to compile.
  -=< FFL is not directly supported in User Filter anymore >=-

+ map_enable / control_enable are set incorrectly on load which
  makes the dialog code inefficient.
  -=< fixed by the new internal handling of filters >=-

+ Filter data is not consistent with stored files.
  -=< fixed by implementation of GUF >=-

+ No octal or sedecimal numbers allowed in code.

+ The rnd() seed reset control is shown even if a filter does
  not use the rnd() function.

+ Transpiler (uf2c) is incomplete, its rtl non-existing.

+ Syntax error: comma operator inside parenthesis

~ The dialog is BIG.

~ Help is incomplete.

- The plug-in cannot edit / alter locale data for the filters.

- Controller and map values can be used on a computed index.
  Overflow is checked, but no run-time error message is given -
  instead the error is silently turned into a zero value for the
  controller / map that is referred to.
  Can also be regarded as a compatibility feature with original
  Filter Factory functionality.

- Channel-width dependant values are hard-coded. This needs to be
  changed for future versions of the plugin in order to support
  wider color channels.
