Add outline view for the ArgFile editor
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Initial work on ArgFile content assist in place. Some work remaining,
including sorting proposals, etc.
Correction to completion of directory paths
Fixes to support content assist on relative paths (eg
+incdir+di<<MARK>>). 
Update to ArgFile content assist to support updir-relative paths
Fix debug-enabled tests
Merge pull request #167 from mballance-sf/master

Add ArgFile outline view and content assist