Makes Matching Sections Case Insensitive

Updates Parser::getSection, Parser::getSectionChildren, and
Section::belongsToReference case insensitive.

Adds Section::normalizeReference to consolidate all the preg_replace
calls to convert dash delimited references to dot delimited references.

Updates Parser::getSection to work with normalized references.
Merge pull request #14 from scaninc/caseInsensitiveSectionMethods

Makes Matching Sections Case Insensitive