added Doxygen target

Added a "doc" target that runs the Doxygen over the project sources. Simply
`make doc` to generate the project's documentation in the `doc` directory.
Merge branch 'master' into iss12
fixed include and libast linking

mwcbendcpkg.cpp was including sqlite3.h instead of sqlite3.hpp. The libast
library did not link against the boost libraries, which caused linker errors.
Merge branch 'master' into iss12
Merge remote-tracking branch 'origin/iss12' into iss12