Added primitive wave shapers (option --shape) allowing to choose sine-like or sawtooth-like shape of wawe in output file created during cas -> audio conversion (the default is to create square wave). For turbo formats only.
Added optional resonant lowpass filter. It selectively amplifies weak parts of the signal without clipping the rest of it. For now works well with AST format.
'pwmc' chunk is now stored according to description
FSK - fixed detection of "long zeros" in some situations.