1. GDB will print cryptic error messages if it is not fed keep-alive packets

1. GDB will print cryptic error messages if it is not fed keep-alive packets
within the last 2000ms.

To fix this, add keep_alive() if you are spending >1000ms in an algorithm
thus holding up the server loop.

target_call_timer_callbacks() invokes keep_alive().

2. post_reset script is now executed at normal JTAG speed and not
reset speed.

3. Resume is now synchronous again. Hopefully it will work this time.

git-svn-id: svn://svn.berlios.de/openocd/trunk@826 b42882b7-edfa-0310-969c-e2dbd0fdcd60