Better UART flowcontrol

1. Better UART flowcontrol. This commit include Rate-limited rx rate that is proprotional to the CPU speed but also boosted by the transmit rate; We can now use RTS hardware handshaking. Hurrah. Note -clocal and +crtscts stty options are required.
1. Removed ace editor github theme (incorrect behavior with last character of a line)
1. Implemented 'cat>prog.c' and 'dd' versions to capture the user's typed code Neither work acceptably (busybox issue?) For now we're stuck with the escaped-echo version. I left the code for both the 'cat >' and 'dd' versions in compile.html so they can be further tested.