Source format specified in debian/source/format to fix a warning

- "make clean" extended.

dpkg-source: warning: no source format specified in debian/source/format, see dpkg-source(1)
dpkg-source: warning: source directory 'netwmpager' is not <sourcepackage>-<upstreamversion> 'netwmpager-1.11'
dpkg-source: info: using source format `1.0'
Warnings reported by lintian fixed

- Standards version increased to latest 3.9.5.
- Clean and distclean targets remove directories too.
- Debian rules build-arch build-indep added.
- Hardening of the executable enabled.

W: netwmpager: hardening-no-relro usr/bin/netwmpager
W: netwmpager source: debian-rules-missing-recommended-target build-indep
W: netwmpager source: debian-rules-missing-recommended-target build-arch
W: netwmpager source: ancient-standards-version 3.8.2 (current is 3.9.5)
Manual page created

- ./configure updated to allow specify man dir.
- Makefile builds and installs the manual page.
- "make install" creates destination directories now.
README formatted using markdown syntax

- Links to screenshots and changelog added to readme.