revert internal png, jpeg, and bmp converters and make them optional

[Dimitar Misev]

Sometimes gdal can be a too big dependency and it is useful to be able to compile only a handful of necessary converters.

The task is to revert the code of jpeg, png, and bmp converters, and allow conditional compilation based on cmake parameters -DUSE_JPEG, -DUSE_PNG, -DUSE_BMP and -DUSE_TIFF.

These converters are invoked with functions jpeg/inv_jpeg, png/inv_png, etc. If gdal support is not compiled in rasdaman, then encode/decode will use these convertors as well if possible.