Rewrite RGBFIX

- Make it work inside pipelines
- Add RGBFIX tests to the suite
- Be more flexible in accepted MBC names
- Add warnings for dangerous or nonsensical input params
- Improve man page

test/fix/old-lic.gb

@@ -0,0 +1,2 @@
+<EFBFBD>EZ/:<3A><><EFBFBD><7F><7F>Ѐ<EFBFBD><02>J/<2F><><EFBFBD><EFBFBD>_<<3C>&<26>A<EFBFBD><41><EFBFBD><EFBFBD><EFBFBD>XgAP 
+`<60>1@Wh<><68>||ø<>e뻬e^"7(*YV<59><56>T<EFBFBD><54><EFBFBD>OY!<21><03><04>̔]<5D><><EFBFBD>=<3D>
<01><>y<EFBFBD>V~x<>a<>]<5D>;<3B><><EFBFBD>¡<EFBFBD>zUm<0C><>z:d@֪<>b<EFBFBD> 'vʆq<02>W<EFBFBD><14>_<EFBFBD><5F><17><><EFBFBD>2)G<05>v(k<><6B><EFBFBD>g,<2C>p*@<40><>!<21>Dõ<44>0k<14><>
<01><><EFBFBD>e<EFBFBD>%ǚod<6F><64><EFBFBD>$r<11><><EFBFBD><<3C>:<3A><>cgi<67>"aF'=f<><66><1F><>EcVcL.03"w),<2C>	HQi<51>D<EFBFBD>f<EFBFBD>3<EFBFBD>s(-$?a0<61>@<40><>.O<>B{y<>z<EFBFBD>ʫ<1A>	h<>/\<0B>S<>]<5D>o<EFBFBD><6F>m'2D#/
gr<67>W3<>Χ<><CEA7>&U<><55><EFBFBD>EgMh<4D>-A<>*6<><36><EFBFBD><EFBFBD><EFBFBD>4M|1<>q0O<30><4F>*$<24>O<EFBFBD>/n<><6E><EFBFBD>g<EFBFBD><67>2R<32><52>Q<EFBFBD>X<>_<07><><EFBFBD>[숔<>p<EFBFBD><70>\<5C>)ƧTS<54>T<EFBFBD>aP*'[<0F>x<EFBFBD><78>>߅<>Ub[Ԧ<>9s<39><73>I<EFBFBD><49>P