Color coded monitor for code, PC, read/write, special locations, and display

[baileyparker]

See #19.

This enhancement adds the following features to the monitor:

• If the last operation retrieved something from memory (not the simulator getting the PC or argument but explicit memory retrieval instruction such as LDA), it is bolded in the output
• If the last operation wrote to memory, it is bolded and colored in green in the output
• The part of memory that is the display is indicated by a transparent highlighting that corresponds to the color in that memory location
• The special memory locations, random and last keypress, are colored pink and purple respectively (and when you perform an instruction on either of their values they are bolded)
• The program in memory is highlighted in yellow (and the instruction to which the PC points is colored orange)

I'm also looking into expanding this to highlight the current instruction and the address or literal that accompanies that instruction.

[BigEd]

I like this idea a lot, but as noted, this (upstream) fork is now in maintenance mode, so I won't merge this request. If you're actively maintaining a fork with a live (gh-pages) branch, I'm happy to link to that URL in the upstream README, perhaps with a summary of what makes it notable.