improve consistency in parsing primitives from strings

The motivation is to provide a simpler and safer means of extracting integers and labels from strings. There are several benefits:

• catch bad label/scalar input for command-line options/arguments which may be human generated or via scripts.
• easier/clear to work with when input has already been lexed, without using an IStringStream()
• work directly with C++ strings instead of C-string.

@andy

changed target branch from master to develop

changed title from Feature string parsing to improve consistency in parsing primitives from strings

added ~22 ~29 labels

assigned to @Sergio

changed the description

added 133 commits

• 32e6759c...677564e9 - 129 commits from branch develop
• 3cb9c66c - STYLE: typo in doxygen string
• 41f59b07 - ENH: improve consistency in parsing primitives from strings (issue #590 (closed))
• 1c649817 - STYLE: avoid IStringStream when parsing primitives
• 13f04876 - ENH: improve input stringency for argList options

Compare with previous version

I've resolved potential merge conflicts

mentioned in commit b2e05dc647496fdb00e172a3319aadc21c7c48cb

merged