kgmlFileName2PathwayName(filename)
NOTE: there is issue of package loading sequence to use this function:
the 'KEGG.db' must be loaded before 'KEGGgraph' to use it
properly. Otherwise the mget
returns error of 'KEGGPATHID2NAME'
is not a environment. So far I don't where does this bug come from, so
I commented out the examples.