File and PECL Header flags are not constants and set on construct. Also, clarified Header Parsing (expanded var), and extended Header Parsing to allow specifying the First-Line name, cutting down on CaseInsensitiveArray usage (heavy).
Allow passing Curl Opts in Constructor.  Support for CurlOpt Array setting.
Added ContentType normalization/parser.
Normalized URL setting in prep for substitutive urls.
Consolidate Setting Request Type and URL.  Add ability for URLs to have placeholders.