Check magic cookies between remote endpoints (#22)

The idea here is to ensure endpoints are properly paired by exchanging
a "cookie." If the source side cookie and destination side cookie
don't match then the transfer will fail immediately. Our inspiration
is XWindows and MIT-MAGIC-COOKIE-1.

This feature won't be useful until the cookie can be set by a command
line option.
Add a '-cookie' CLO to set the magic cookie (#22)

This commit fixes #22.
Merge pull request #40 from ORNL/fix-22

Fix #22
Heartbeat fixed on destination side.
Fix -datapattern random regression

All of the datapatterns were broken and this commit fixes them.
Fixes #43.
Fix minor autoconf thing

The checks for patch and tar didn't really fail the configure, now
they do.
Fix #41 gitignore issue

Clean up paths, and extraneous ignore file.
Fix #33 make check fails sometimes

Make check now has dependencies that are a little better seperated,
and

make clean
make check

succeeds.
Fix #36 Verify doesn't work

Verify has never worked.  So fo rnow, make that option invisible.
There is no plan to re-enable it.
Modified the flow to put heartbeat options on the sink. And, password prompt uses the machine name given by the user.
Updated unit tests to accommadte the changes to xddmcp.
Fixed issue with source as a directory link.
Remove dependency on E2E header
Merge branch 'master' into multinic

Conflicts:
	src/common/end_to_end.h
	src/net/end_to_end.c

Magic cookie support was removed. Heartbeat is probably broken.