Add new osmo-config-merge utility

This utility allows you to merge an incremental config "patch"
into an osmocom-style config file.

The patch file follows the same syntax as the original config file.

It works by appending the leaf nodes of the patch file to the respective
nodes of the input config file.

This process allows configuration file changes/updates to be performed
in a more stable/reliable way than by means of [unified] diff files,
as they break every time the context lines break.

osmo-config-merge doesn't suffer from this problem, as it understands
the tree-like nature of VTY config files.

NITE: This only works with configuration files that have proper
indenting, i.e. every level in the hierarchy must be indented excatly
one character, not multiple.

Change-Id: I61997a3668cc3a40d12ca023272f6d782e6fbefe
diff --git a/debian/control b/debian/control
index 540a8b5..33ae2d4 100644
--- a/debian/control
+++ b/debian/control
@@ -315,7 +315,8 @@
 Description: Utilities for gsm
  This package contains a program for frequency calculation for GSM called
  'osmo-arfcn' and a program called 'osmo-auc-gen' that is used for testing GSM
- authentication.
+ authentication, as well as 'osmo-config-merge', a tool for merging Osmocom
+ configuration files.
  .
  They use the libosmocore library. The libosmocore library contain various
  utility functions that were originally developed as part of the OpenBSC