PCX::Encode doesnt check against max buffer size

[pskelton]

Describe the bug PCX encoding functions never check for buffer overrun

Expected behavior Throw error if buffer size exceeded

[CkNoSFeRaTU]

Also we need to just pass pointer and move output's buffer allocation to encoder so it can properly allocate required buffer according to requested encoding format and image resolution. And get rid of all these hardcoded buffer sizes.