* Run cargo fmt and apply clippy lints from rust 1.51.0
* Rename can_perform_single_line_analisys to try_perform_single_line_analisys and streamline body
* Remove ops::Add impl for CodeStats; only AddAssign is meaningful and used
* Add embedding module to cache heuristic regexes used to detect embedded languages
* Add separate embedding tests; Not all cases can be execised with a single test
* Simplify html embedding test file_triggeringprincipal_frame_1.html until quoting issues are resolved