Prevent collisions when replacing placeholders

Block parser implemented (issue #6)
Prevent collisions when replacing placeholders

parseBlockByPlaceholders method changed from static to member (issue #6)
Prevent collisions when replacing placeholders

Caching the result of template block parsing (issue #6)
Prevent collisions when replacing placeholders

Placeholder replacement reimplemented (issue #6)
Merge pull request #12 from mcarrowd/feat_n6

Prevent collisions when replacing placeholders with data (feature #6)