Make sure series_name_plain is really plain (#1611)
Make sure series_name_plain is really plain (#1611)

[fix] npo_watchlist: properly strip/convert invalid Windows characters
JorisDeRieck/Flexget,sean797/Flexget,tobinjt/Flexget,Danfocus/Flexget,malkavi/Flexget,OmgOhnoes/Flexget,LynxyssCZ/Flexget,poulpito/Flexget,crawln45/Flexget,jawilson/Flexget,sean797/Flexget,JorisDeRieck/Flexget,qk4l/Flexget,Flexget/Flexget,gazpachoking/Flexget,Flexget/Flexget,malkavi/Flexget,OmgOhnoes/Flexget,jawilson/Flexget,jacobmetrick/Flexget,drwyrm/Flexget,crawln45/Flexget,sean797/Flexget,JorisDeRieck/Flexget,ianstalk/Flexget,OmgOhnoes/Flexget,malkavi/Flexget,jacobmetrick/Flexget,jawilson/Flexget,LynxyssCZ/Flexget,qk4l/Flexget,jacobmetrick/Flexget,qk4l/Flexget,Danfocus/Flexget,crawln45/Flexget,ianstalk/Flexget,JorisDeRieck/Flexget,poulpito/Flexget,gazpachoking/Flexget,tobinjt/Flexget,crawln45/Flexget,poulpito/Flexget,Danfocus/Flexget,drwyrm/Flexget,drwyrm/Flexget,malkavi/Flexget,tobinjt/Flexget,tobinjt/Flexget,LynxyssCZ/Flexget,LynxyssCZ/Flexget,ianstalk/Flexget,Flexget/Flexget,Flexget/Flexget,Danfocus/Flexget,jawilson/Flexget