Issue #2863652 by alexpott, anmolgoyal74, javi.pl, dww, zaporylie,...

Issue #2863652 by alexpott, anmolgoyal74, javi.pl, dww, zaporylie, moinak_dutta, iampuma, a.dmitriiev, benjifisher, Pancho, larowlan, yoroy: Do not allow files with "php|pl|py|cgi|asp|js" extensions to be renamed to *.txt and be uploaded if *.txt is not allowed by the field widget