opensc-explorer: add 'echo' command
opensc-explorer: add 'echo' command

Add 'echo' command that simply displays its arguments.

With the recently committed script interpreter feature and this echo command,
nice litte scripts can be written, like e.g.

 $ cat opengpg-userinfo
 #!/usr/bin/opensc-explorer
 cd 0065
 echo Name:
 cat 005B
 echo Language:
 cat 5F2D
 echo Gender:
 cat 5F35
 quit

ieugen/OpenSC,adminmt/OpenSC,dirkx/OpenSC.tokend,tidatida/OpenSC,metsma/OpenSC,rickyepoderi/OpenSC,dirkx/OpenSC.tokend,viktorTarasov/OpenSC-SM,aobaid/OpenSC,velter/OpenSC,philipWendland/OpenSC,marschap/pkg-opensc,martinpaljak/OpenSC,viktorTarasov/OpenSC-SM,fabled/OpenSC,OpenSC/OpenSC,kasparsd/opensc-latvia-id,0x7678/myOpenSC,hongquan/OpenSC-main,germanblanco/OpenSC,kasparsd/opensc-latvia-id,UIKit0/OpenSC,AktivCo/OpenSC,hhonkanen/OpenSC,aobaid/OpenSC,financeX/OpenSC,financeX/OpenSC,carlhoerberg/OpenSC,dirkx/OpenSC.tokend,aobaid/OpenSC,financeX/OpenSC,CardContact/OpenSC,adminmt/OpenSC,ieugen/OpenSC,frankmorgner/OpenSC,carlhoerberg/OpenSC,dengert/OpenSC,fabled/OpenSC,mouse07410/OpenSC,marschap/pkg-opensc,Jakuje/OpenSC,adminmt/OpenSC,kasparsd/opensc-latvia-id,tidatida/OpenSC,philipWendland/OpenSC,frankmorgner/OpenSC,philipWendland/OpenSC,jpki/OpenSC,ieugen/OpenSC,carlhoerberg/OpenSC,0x7678/OpenSC,AktivCo/OpenSC,frankmorgner/OpenSC,carlhoerberg/OpenSC,velter/OpenSC,nmav/OpenSC,Jakuje/OpenSC,Jakuje/OpenSC,rickyepoderi/OpenSC,mtrojnar/OpenSC,LudovicRousseau/OpenSC,OpenSC/OpenSC,adminmt/OpenSC,gemini/OpenSC,LudovicRousseau/OpenSC,OpenSC/OpenSC,mouse07410/OpenSC,dengert/OpenSC,0x7678/OpenSC,metsma/OpenSC,martinpaljak/OpenSC,nmav/OpenSC,0x7678/myOpenSC,dengert/OpenSC,0x7678/OpenSC,jpki/OpenSC,fabled/OpenSC,hongquan/OpenSC-main,metsma/OpenSC,dirkx/OpenSC.tokend,mtrojnar/OpenSC,gemini/OpenSC,mtrojnar/OpenSC,germanblanco/OpenSC,Jakuje/OpenSC,financeX/OpenSC,0x7678/OpenSC,l1k/OpenSC,UIKit0/OpenSC,gemini/OpenSC,0x7678/myOpenSC,CardContact/OpenSC,viktorTarasov/OpenSC-SM,dirkx/OpenSC,tidatida/OpenSC,frankmorgner/OpenSC,AktivCo/OpenSC,carlhoerberg/OpenSC,tidatida/OpenSC,velter/OpenSC,jpki/OpenSC,marschap/pkg-opensc,martinpaljak/OpenSC,LudovicRousseau/OpenSC,0x7678/myOpenSC,aobaid/OpenSC,UIKit0/OpenSC,marschap/pkg-opensc,fabled/OpenSC,hhonkanen/OpenSC,velter/OpenSC,l1k/OpenSC,CardContact/OpenSC,UIKit0/OpenSC,mouse07410/OpenSC,l1k/OpenSC,germanblanco/OpenSC,hongquan/OpenSC-main,hhonkanen/OpenSC,rickyepoderi/OpenSC,ieugen/OpenSC,dirkx/OpenSC,dirkx/OpenSC,0x7678/myOpenSC,dirkx/OpenSC,kasparsd/opensc-latvia-id,dirkx/OpenSC.tokend,dirkx/OpenSC.tokend,financeX/OpenSC,nmav/OpenSC,ieugen/OpenSC,dirkx/OpenSC