GXemul Code2

Updating NetBSD/cats installation instructions from 8.0 to 8.1.

Enabling a MIPS instruction combination for memset which was previously not used, and making it and and strlen instruction combination work with 64-bit mode too. Also describing why not both lb and lbu need to be handled in the strlen_lb_addiu_bne_nop fallback case. (Not much performance improvement in practice, but still.)

The MIPS ALU instruction variants with hardcoded register offsets was not committed; did not improve performance in real-world tests.

Adding link to NetBSD mailing list about lack of X server in 8.x.

Minor update.

Fix file names.

Fixing size overflow.

Minor comments.

Upgrading the NetBSD/hpcmips installation instructions from 8.0 to 8.1. Good news: graphics works again for more MobilePro models. Also adding an automated expect regression test.

Rounding up disk image sizes to full cylinders; fixes a bug where guest OSes could fail to read the end of e.g. a .tar.gz file supplied as a disk image on the command line.