Add a refactoring to switch between "string" and @"verbatim string"

Also add the necessary infrastructure to unit-test refactorings
Add help links and descriptions to analyzers

For some of them I didn't had any good description that
wasn't a repetition of the text so I avoided to add it
but still added the help link to all of them.

While reviewing all of them I also added the tag to get
greyed-text on analyzer indicating unnecesary constructs:

    customTags: WellKnownDiagnosticTags.Unnecessary

Follow the discussion in #78
Ensure that comments are kept in the refactoring
Merge pull request #94 from vbfox/descriptions-and-help-links

Add help links and descriptions to analyzers
Merge pull request #93 from vbfox/string-types-refactoring

Add a refactoring to switch between "string" and @"verbatim string"
Remove the string type refactoring

It'll be Re-introduced as an analyzer following #66.
Add an analyzer/fix for verbatim & Regular strings

The analyzer add a diagnostic to regular strings ("Hello") and verbatim
ones (@"Hello") and the code fix suggest for each one to convert to the
other.

This code was a refactoring but converted to a code fix after discussion
in #93 following the decision of #66.
Add missing help links for string representation analyzer
clean up readme, direct users to site
analyzer, codefix and tests for converting to expression bodied member when applicable (closes #101)
Merge pull request #105 from ElemarJR/ConvertToExpressionBodiedMember

converting to expression bodied member when applicable (closes #101)
FIX: Throws exceptions with empty methods
Add parameter
Add test parameter
Update test parameter
move analyzers, code fixes and tests into category folders, #97
analyzer, codefix and tests for 'Invert For' (closes #87)
Update test parameter
make small reformatting in 'invertfor', #87
Merge branch 'ElemarJR-InvertFor'