gh: update Tcl9 test case to final 9.0.0
Disable pager when running for script language
doc: suggest use of lightweight test suite in INSTALL
gh: update Tcl9 test case to 9.0.0rc1
Make "resource temporarily unavailable" an external error
ts: fix asynchronous tests to correctly retrieve exit code
ts: adapt testall_cmd/testall_cmd_re to eval all shells
ts: check exit code 1 on bad module command or eval