added a heartbeat.

A heartbeat makes a led blink. This task has the lowest priority so if
there is any lock the led will stop blinking.
fixed C sources in Makefile.

forgot to change the name of a file in the Makefile.
changed tcp/ip uart speed.
added an led to indicate flush.
Revert "workaround for altera lack of rw support."

This reverts commit 0456bc0d87ee1473a25ceb261f39735cc1ea665f.

I did this to try a new approach.

Conflicts:
	serial_io.c
UART read / write operation.
cleanup of echo app.
re-enabled echo app for testing.