Nuke std::wstring from plDynamicTextMsg
pyDynamicMap plString-ification

We now no longer care if the scripter hands us a string object or a
unicode object! Please note that drawTextW was thrown away because it is
now redundant.
pyDynamicMap header tweaks...

More spurious virtual keywords removed
Merge pull request #425 from Hoikas/dyntextmsg-string

pyDynamicMap plString-ification