added YCode conversion

evaluate the code and return the result

needed for converting e.g.
SCR::Read(.target.yast2, "languages/language_cs_CZ.ycp")
results

- fow unknown types put also the type to the exception message
Merge pull request #16 from lslezak/code_conversion

Added YCode conversion
fix setting WFM::ARGS
do not provide detail backtrace in case index on nil
fix lastnotof
fix log compatibility
fix loading path to proper work of topath builtin
fix sformat when String module is loaded
fix sformat and tostring builtin