Add pkgset helpers

Ported some code from apt cacheset.cc to populate a pkgset.
The function pkgset_from_string will fill a given pkgset with
either the exactly named package, or the packages matched by a
string predicated by is_pattern.

In the future, we should look to directly use the apt cacheset
infrastructure.  This is currently blocked by our custom
implementation of pkgCacheFile (see aptcache.h).

Errors that occur in looking up the package (such as no package
with that name, or an invalid search pattern) are pushed to
the global error list with a customizable error_type (default:
ERROR).

1 files changed, 5 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 85bf1ef0..2bb1bc62 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,11 @@
 [6/8/2012]
 Version 0.6.9                               "All in a days work"
 
+- Internal changes:
+
+  * Unified the way packages are selected from command line
+    arguments.
+
 [5/11/2012]
 Version 0.6.8                               "Never need a reason,
                                              never need a rhyme"