So that shell scripts do not blunder on after errors.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

bugfix in blink.sh - wring pin
improving the maxdetect routing - a little.
gpio pins

Added in generic 'blink' programs in the examples in C, RTB and Shell.
Updated wiringPi with a little big-file on the millis() function and
added in a new micros() function too.
Updated the examples with standard LGPL headers.
Added a new isr-osc.c test program - just for ISR timing purposes.

Also Makefile tweaks to help improve things somewhat - decided to
read the Makefile manual after some 15 years to updated my make
grey cells somewhat.

New command in the gpio command - readall