czx81 - Curses ZX81 emulator

Age	Commit message (Expand)	Author
2020-03-30	Changed global variable name so it builds on FreeBSD.	Ian C
2020-03-22	Added load/save and some extra instructions.	Ian C
2020-03-21	Updates to instructions and fix to keyboard table.	Ian C
2020-03-20	Added extra keys.	Ian C
2020-03-20	Basic keys added and now being read.	Ian C
2020-03-19	First attempt at display routine. Still keyboard handling to do.	Ian C
2020-03-18	Added framework of ZX81 code. Still to do screen draw and key handling.	Ian C
2020-03-16	Added Z80 code from DS81.	Ian C
2020-03-15	Added simple timing to get 50 frames a second, hopefully.	Ian C
2020-03-13	Added skeleton source file and Makefile.	Ian C