Use complete Debian revision number as build number

Use complete Debian revision number as build number, instead of
just the numeric part. Also, re-implement scripts/time-stamper.bash
without direct calls to dpkg-parsechangelog.

debian/patches/17-fix-all-but-deprecated-api-warnings.patch

@@ -22,7 +22,7 @@ This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
  9 files changed, 38 insertions(+), 32 deletions(-)
 
 diff --git a/closure.c b/closure.c
-index 7568cba..0e2f889 100644
+index 51e91a2..40bb225 100644
 --- a/closure.c
 +++ b/closure.c
 @@ -196,7 +196,7 @@ void ReadDotfile()