patman: Add support for settings in .patman

This patch adds support for a [settings] section in the .patman file.
In this section you can add settings that will affect the default
values for command-line options.

Support is added in a generic way such that any setting can be updated
by just referring to the "dest" of the option that is passed to the
option parser.  At the moment options that would make sense to put in
settings are "ignore_errors", "process_tags", and "verbose".  You
could override them like:

 [settings]
 ignore_errors: True
 process_tags: False
 verbose: True

The settings functionality is also used in a future change which adds
support for per-project settings.

Signed-off-by: Doug Anderson <dianders@chromium.org>
diff --git a/tools/patman/README b/tools/patman/README
index 16b51eb..2743da9 100644
--- a/tools/patman/README
+++ b/tools/patman/README
@@ -98,6 +98,22 @@
 used. Failing that you can put it into your path or ~/bin/checkpatch.pl
 
 
+If you want to change the defaults for patman's command-line arguments,
+you can add a [settings] section to your .patman file.  This can be used
+for any command line option by referring to the "dest" for the option in
+patman.py.  For reference, the useful ones (at the moment) shown below
+(all with the non-default setting):
+
+>>>
+
+[settings]
+ignore_errors: True
+process_tags: False
+verbose: True
+
+<<<
+
+
 How to run it
 =============