Rewrite the Txt2tags parser for better conformance and features

This fixes parsing indented titles and titles with embedded delimiter
characters, and adds support for title nesting information.

Syntax: http://txt2tags.org/rules.html

Closes [feature-requests:#690].
Add a Txt2tags test case

From the official docs:
https://txt2tags.googlecode.com/svn/trunk/doc/English/rules.t2t
Add a Txt2tags test case

From the official docs:
https://txt2tags.googlecode.com/svn/trunk/samples/sample.t2t
Add a Txt2tags test case for titles

This is simply extracted from the rules.t2t test, but with unique title
content as the tagmanager removes duplicate tags in tags files.
Merge pull request #319 from b4n/better-txt2tags-parser

Better txt2tags parser