Added trivial interface to expose the AST to a library

* Modified the unix makefile to build a static parser/converter library as intermediate step
* Split the parse and convert function into separated functions
* Exposed the relevant memory management ("free") function
Fix a buffer overrun warning in Loose List parsing

Use strncat instead of strcat
Merge branch 'mem_fixes' of https://github.com/jibee/MultiMarkdown-4