Some improvements for debugging tools

[elad335]

• Fix a segfault when viewing unmapped memory as image in memory viewer, simply do nothing in this case. Also use super ptr because non-emu threads do not support rsx access violation handling.
• Remove one '>' or space from the disassembler view, there were 4 characters reserved only for breakpoints which looked weird imo, now there are only 3.
  Also make it consistent with 'no thread' view, add the remaining 3 spaces there as well.
• Fix memory leaks regarding wrong usage of QImage passed raw pointers in rsx debugger and memory image viewer.
• Fix a corner case when viewing unaligned spu memory at the end of SPU LS by force aligning the address to 4 bytes. For non-aligned memory view the proper memory viewer tool should be used instead of the disassembler.
• Avoid a segfault when reading ppu stack contents in debugger.