version 1.6.0

See
http://forums.radioreference.com/digital-voice-decoding-software/256111-
dsd-1-6-closed-fork-open-source.html#post1884783
new options to control filters and P25 encrypted signals

I have added the -l and -pu options.
Merge commit '20271c6df57dacbaed3f2255a8230f44f58bd3ae'

Apparently when 1.6.0 was release it was not properly merged. This re-add the disable p25 encryption muting flag.

Conflicts:
	README
	dsd.h
	dsd_main.c
	dsd_symbol.c
	p25p1_ldu1.c
	p25p1_ldu2.c
Change current work to v1.7.0-dev
Add git tag / SHA1 as a build string

Every build from commit 20271c6 (Apr 10 2013) is versioned as 1.6.0.
Add a build version after the version number
Digital Speech Decoder 1.6.0 (build:v1.6.0-20-g16110bd)

The build string uses git describe to list the tag closest to head,
and the number of commits past that tag, the a litteral g and ending
with the current SHA1