recognize xBase sources
recognize xBase sources

[xBase: https://en.wikipedia.org/wiki/xBase]

Reopened PR 593 with the two language additions split off.
alitalia/linguist,github/linguist,meunierfrederic/octocatlinguist,pchaigno/linguist,JJ/linguist,ya7lelkom/linguist,0a-/linguist,alvarotrigo/linguist,matt40k/linguist,sagar290/linguist,SRI-CSL/linguist,steventhanna/linguist,iblech/linguist,yyx990803/linguist,c-lipka/linguist,scttnlsn/linguist,stanhu/linguist,assimovt/ling-ist,yyx990803/linguist,kyoungrok0517/linguist,ChaiScript/linguist,JJ/linguist,FStarLang/linguist,alvarotrigo/linguist,github/linguist,PsichiX/linguist,davidzchen/linguist,MahmoudFayed/linguist,sideci-sample/sideci-sample-linguist,pcantrell/linguist,matt40k/linguist,martynbm/linguist,mcandre/linguist,manveru/linguist,phpsgi/linguist,scttnlsn/linguist,anhongyue/test222,seanders/linguist,stanhu/linguist,Rockyspade/linguist,JJ/linguist,cybernet14/linguist,MadcapJake/linguist,yscho/linguist,erkyrath/linguist,phpsgi/linguist,github/linguist,jrnold/linguist,jrnold/linguist,ilyes14/linguist,yscho/linguist,seanders/linguist,CoderXpert/linguist,Rockyspade/linguist,hcutler/linguist,ammaraskar/linguist,jjatria/linguist,bluebear94/linguist,cokeboL/linguist,meunierfrederic/octocatlinguist,mattn/linguist,JJ/linguist,FStarLang/linguist,hcatlin/linguist,thejameskyle/linguist,jjatria/linguist,c-lipka/linguist,kr/linguist,ilyes14/linguist,pcantrell/linguist,R4PaSs/linguist,christop/linguist,sagar290/linguist,MahmoudFayed/linguist,marcojonker/test,marcojonker/test,ppaulweber/github-linguist,adamkaplan/linguist,chiranjeevjain/linguist,MadcapJake/linguist,georgesuperman/linguist,BerkeleyTrue/linguist,osorgin/linguist,mcandre/linguist,jtbandes/linguist,meunierfrederic/octocatlinguist,erkyrath/linguist,CegepVictoriaville/linguist,igat259/linguist,ppaulweber/github-linguist,wcandillon/linguist,manveru/linguist,erkyrath/linguist,anhongyue/test222,osorgin/linguist,yyx990803/linguist,mattn/linguist,cybernet14/linguist,sebgod/linguist,nburkley/linguist,sideci-sample/sideci-sample-linguist,a0viedo/linguist,MostAwesomeDude/linguist,stanhu/linguist,assimovt/ling-ist,martynbm/linguist,PsichiX/linguist,CoderXpert/linguist,yyx990803/linguist,sebgod/linguist,Mx7f/linguist,douglas-larocca/linguist,christop/linguist,pchaigno/linguist,tschf/linguist,sebgod/linguist,wcandillon/linguist,pchaigno/linguist,Mailaender/linguist,SRI-CSL/linguist,Mx7f/linguist,tschf/linguist,mwpastore/linguist,adamkaplan/linguist,iblech/linguist,ya7lelkom/linguist,mwpastore/linguist,blakeembrey/linguist,alitalia/linguist,jtbandes/linguist,a0viedo/linguist,CegepVictoriaville/linguist,nburkley/linguist,georgesuperman/linguist,steventhanna/linguist,pchaigno/linguist,kyoungrok0517/linguist,maxogden/linguist,hcutler/linguist,R4PaSs/linguist,cokeboL/linguist,erkyrath/linguist,Ocramius/linguist,bluebear94/linguist,0a-/linguist,hcatlin/linguist,MostAwesomeDude/linguist,blakeembrey/linguist,thejameskyle/linguist,github/linguist,kr/linguist,whitj00/linguist,whitj00/linguist,sebgod/linguist,chiranjeevjain/linguist,ammaraskar/linguist,davidzchen/linguist,BerkeleyTrue/linguist,stanhu/linguist,douglas-larocca/linguist