ref: 611dced75f0a6c9fd4b35b88ee0dd9ac5806cb54
dir: /appl/cmd/sh/doc/History/
14/11/96 started
12/12/96 first mostly working version
13/12/96 fixed bug in builtin_if
14/12/96 prompt fixed, dup fixed.
17/1/97 fiddled with shell script perm checking
16/2/97 converted to yacc grammar
18/2/97 got pipes and backquotes working, with only minor hacks...
2/4/00 revamped:
single process, single main module; added load builtin; added ${} operator;
added eval and std modules
17/4/00 added '=' and ':=' operators; removed builtin 'set' and 'local'.
11/6/00 added tuple assignment
2/3/01 added n-char lookahead in lexer; ':' no longer so special
15/2/01 store environment variables in standard quoted format.