compile.html (with pause buttons) plus a flow-controlled uart (xon,rts,dtr and rate-limite support)

Here's three things:

1. A compile.html with simple pause/reset buttons. 

1. A uart with register debugging info + rx flow control (xon,dtr,cts, and rate limit hack) -at least to the best of my understanding of the hardware spec. if you are going to play with this then 
stty [-]clocal
stty crts
stty xoff
might be useful. Plus enable the verbose logging in uart.js to see the register bitwise changes.

1. A bigfile.c for testing large (>4K) transfers.

I was able to get large file transfers working somewhat reliably, but not perfectly, by artificially limiting the transfer rate (see comments inside uart.js)

Uart receiving can be switched off and on based on the three standard flow control mechanisms (mentioned above) plus a dubious hack that assumes the CPU can process a given number of chars every execute() cycle.

I noticed the kernel term device will emit xon/xoff chars when the buffer gets full. I have not yet tried changing the term.js mode to use them again. Certainly without the new rate-limiting code they were insufficient (they were transmitted too late; we're already overwritten the kernel buffer)

I wanted to turn off terminal echo during the upload. however "stty echo' did not turn the terminal output back off when required (before "gcc") - see the .html file if you want to play with this.

The compile.html could be polished to include a header and focus and include some drop-down examples. We should probably set the initial focus on the textarea.

I need to turn my attention to other tasks in the near future so, feel free to throw this out. Perhaps someone on openrisk could take a look at the uart problem?


Best,
Lawrence.