add support for [info source ?filename line?]

Allows a script to be created with explicit source info

Signed-off-by: Steve Bennett <steveb@workware.net.au>
jim: change the output of errorInfo

Rather than "Runtime Error: <file>:<line>: ...", use
use "<file>:<line>: Error: ..."

This latter format is both shorter and more consistent with other tools (e.g. gcc).
This also allows errors to be reported with the default errorfmt of vim's quickfix feature.

Signed-off-by: Steve Bennett <steveb@workware.net.au>
signal: don't define more than NSIG signals

If NSIG is defined, limit the number of supported signals to that number

Signed-off-by: Steve Bennett <steveb@workware.net.au>
aio: fix a compiler warning on some platforms

Signed-off-by: Steve Bennett <steveb@workware.net.au>
glob: remove some leftover unused code in glob.tcl

Signed-off-by: Steve Bennett <steveb@workware.net.au>