CG types are typedefs for NS type only in 64-bit mode and
different types in 32-bit.

CGGradientCreateWithColorComponents accepts CGFloat as parameter,
which can be either double or float. TGColorGradient works with Double_t.
Make it work with CGFloat == float.

ivars hidden in @implementation part are 64-bit only thing.
move them into headers (@interface).

if -fk is specified, the target file contain the baskets with the same compression as in the input files
  unless -O is specified.  The meta data will be compressed using the compression level specified in the first
  input or the compression setting specified follow fk (206 when using -fk206 for example)
if -ff is specified, the compression level use is the one specified in the first input.