README: Add some more description.

README/CHANGES: Clean up, remove BitBucket links.

openmsx: Set max frameskip to speed up boot time.

neonlib/gunzip: Update.

README: Glass requires Java 8, and plural fix.

neonlib: Update to latest.

neonlib: Update to fix potentially serious disabled interrupts bug.

Though by chance it seemed to be unaffected.

COM: Update gunzip and include Adler32 check in compilation.

neonlib/gunzip: Update.

Mapped32KWriter: Use plain GetSlot / SetSlot.

PNGViewer: Extract ShowProgressive method.

PNGViewer: Remove (Z80 version) comment.

Cause there is no R800 version… it didn’t really make that much of a difference,
32 R800 cycles vs. 14 with MULUB, and it would’ve complicated the code.

openmsx.tcl: Comment out the 0H read/write watchpoints.

Because they don’t work with the current condition.

PNGViewer: Keep line loop counter in b instead of c.

PNGViewer: Center the image.

PNGScanner: Support images whose scanlines do not fit in the buffer.

Like an RGBA image with width > 256.

PNGScanner: Optimise filter looping.

By using two nested 8-bit loops.

PNGViewer: Support palette transparency.

PNG: Ensure ProcessPLTEChunk returns no carry.

PNG: Reorder code to minimise relative jump distance.