User gmdate() instead of date_i18n().

This is only for the legacy dates fields. Using date_i18n() was applying
the current timezone offset which was causing the dates to output
incorrectly because the dates were created with gmmktime() without a
timezone offset applied. From Google searches, if you use gmmktime() to
create a timestamp you should use gmdate() display it.
Fix spelling!
Fix grammer.
Add the initial character URL structure settings.
Code cleanup of cnFormatting::sanitizeString().
Code cleanup of cnFormatting:: sanitizeStringStrong().
Code cleanup of cnFormatting::stripNonNumeric().
Code cleanup of cnFormatting::toBoolean().
Code cleanup of cnFormatting::toYesNo().
Remove % from strings run thru cnFormatting::sanitizeStringStrong().
Remove the sanitize funtion declared within cnRegisterSettings::flushRewrite()

This function ends up in a global scope and because of its generic name
could cause conflicts. Instead we'll use the
cnFormatting::sanitizeStringStrong() method instead. I should have done
this from the beginning.
Rename cnRegisterSettings::flushRewrite().
Add rewrite rules for initial char support.
Retrieve the query var for cn-char in cnRetrieve::entries().
Escape the cn-char query var.
Add cn-char to the pagination template part.
Complete query by initial character.

* Check for string length instead of empty when working the query var.
* Rename cnTemplete::characters() to cnTemplate::index().
* Update PHPdoc in both cnTemplate::index() and
cnTemplate::currentCharacter().
* Add current character check to cnTemplate::index() and set a class on
the anchor to make CSS styling easy.
* Add new method cnTemplate::currentCharacter(). Current this just
outputs a hidden form input that is set with the current charcter if
found.