Add string property to CLI .xslt to retrieve Qt text field
Update doxygen table and string maps to vectorValueProperty.

For issue #306.
Trim CLI string parameter values, so that if empty, the parameter name is not passed to backend
CLI pass explicit empty string

For issue #307.
Removed unnecessary #include <iostream>

For issue #307.
Don't substitute command line arg with default

For issue #307, as user may have explicitly removed the default.
Merge branch '306-cli-string-not-passed-to-backend'

Closes #306.
Merge branch '307-cli-empty-string-not-rejected'

Closes #307.