refactored cwe476 to add stack tracking

adds check_path flag to cwe_checker for finding paths from user input functions to CWE hits.

* Added more documentation to checks

* Corrected typo in opam files

* Added documentation command to makefile

* updated documentation build command in Readme.md

* Fixed some documentation typos

* rand without srand is always treated as an anti-pattern.

* delete generated documentation on "make clean"

* improved CWE476-check with dataflow analysis

This adds a check for CWE248: Uncaught Exception

checks. Ready to implement partial analyses.