msi: Source code reformatting, typo fixes, unify messages

Added lots of debug tracing macros.
Release notes.

documentation/RELEASE_NOTES.html

@@ -16,6 +16,14 @@
 
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+<h3>Improvements to msi</h3>
+
+<p>In addition to fixing its response to discovering parsing errors in its
+  substitution input file (reported as Launchpad
+  <a href="https://bugs.launchpad.net/epics-base/+bug/1503661">bug #1503661</a>)
+  so it now deletes the incomplete output file, the msi program has been cleaned
+  up a little bit internally.</p>
+
 <h3>All array records now post monitors on their array-length fields</h3>
 
 <p>The waveform record has been posting monitors on its NORD field since Base