Add pager detection by using `which` command
Add pager detection by using `which` command

Fix issue #743 (pager gives warnings `Missing filename ("less --help"
for help)`)

Signed-off-by: Kyrylo Silin <6129bf6f04030cd1423e4f3df28402e79fbf30a4@gmail.com>

shockone/pry,jasnow/pry,tdg5/pry,tdg5/pry,jasnow/pry,caporta/pry,gfvcastro/pry,nju520/pry,shockone/pry,scalixte-mdsol/pry,ngpestelos/pry,pvdb/pry,85x14/pry,nju520/pry,printercu/pry,jasonm23/pry,raeno/pry,ooohiroyukiooo/pry,ngpestelos/pry,sideci-sample/sideci-sample-pry,ooohiroyukiooo/pry,bronzdoc/pry,nju520/pry,tdg5/pry,pvdb/pry,josue804/debunker,richo/pry,sferik/pry,printercu/pry,shockone/pry,jasonm23/pry,raeno/pry,geoffreylitt/pry,85x14/pry,raeno/pry,ooohiroyukiooo/pry,sferik/pry,jasonm23/pry,bronzdoc/pry,jasnow/pry,gfvcastro/pry,icebreaker/pry,icebreaker/pry,geoffreylitt/pry,josue804/debunker,caporta/pry,deivid-rodriguez/pry,scalixte-mdsol/pry,85x14/pry,caporta/pry,scalixte-mdsol/pry