[CLEANUP] Fix typos and non-camel-casenesses.

Some variable names and comments have typos in them. In addition, this
change changes all variable names to correct camelCase and replaces
abbreviations by their full words.
[CLEANUP] Add PHPDoc comments to methods and fields.

This change also adds type hinting for arrays.
[CLEANUP] Shift a blank line to the right position.
[CLEANUP] Escape all backslashes in strings

By convention, all backslashes in strings (both single-quoted and
double-quoted) should be escaped by another backslash unless the backslash
is explicitly used for escaping a character for PHP.
Merge pull request #4 from oliverklee/cleanup/typos

[CLEANUP] Fix typos and non-camel-casenesses.
Merge pull request #6 from oliverklee/cleanup/backslashes

[CLEANUP] Escape all backslashes in strings
Merge branch 'cleanup/variables' of https://github.com/oliverklee/emogrifier into oliverklee-cleanup/variables

Conflicts:
	emogrifier.php