use `typeset` instead of `local` in rbenv() function
use `typeset` instead of `local` in rbenv() function

This is to insure portability to ksh.

Fixes #205, references #209

lozybean/rbenv,michael-gabenna/rbenv,dongguangming/pyenv,takluyver/pyenv,yogeshkakde/rbenv,bradynpoulsen/rbenv,almog/rbenv,janusnic/rbenv,Plaristote/rbenv,michael-gabenna/rbenv,genome-vendor/pyenv,genome-vendor/pyenv,beck/rbenv,jeremy/rbenv,chenfengyuan/pyenv,cehoffman/luaenv,peterpih/rbenv,sanemat/rbenv,docwhat/rbenv,jmatbastos/rbenv,yyuu/pyenv,cdlm/rbenv,royratcliffe/rbenv,syndbg/goenv,syndbg/goenv,howtolearntocode/rbenv,pyenv/pyenv,peterpih/rbenv,sebhahn/pyenv,peterhoeg/rbenv,VShangxiao/pyenv,mediadoneright/rbenv,asaaki/rsenv,nobyuki/rbenv,hlecuanda/pyenv,habinmusic/pyenv,UCASREN/pyenv,rridhan/rbenv,recruit-mtl/pyenv,SamuraiT/rbenv,Angeldude/rbenv,peterpih/rbenv,dnsd/pyenv,OiNutter/nodenv,yyyc514/rbenv,rowhit/pyenv,obimod/pyenv,princeofdarkness76/rbenv,pumpkineater/rbenv,obimod/pyenv,hauleth/rbenv,SamuraiT/rbenv,dark5un/nodenv,OiNutter/nodenv,ffdc-scm/rbenv-x86_64-linux,codesdk/rbenv,jeremy/rbenv,sstephenson/rbenv,SamuraiT/rbenv,michael-gabenna/rbenv,sebhahn/pyenv,josegonzalez/rbenv,andrew-christianson/rbenv,jmatbastos/rbenv,stivenrgalvis/rbenv,jmatbastos/rbenv,docwhat/rbenv,BanzaiMan/pyenv,dongguangming/pyenv,edubkendo/rbenv,howtolearntocode/rbenv,RinSer/rbenv,takluyver/pyenv,drakmail/rbenv,princeofdarkness76/rbenv,bradynpoulsen/rbenv,fly19890211/pyenv,jmatbastos/rbenv,rfnash/rbenv,pyenv/pyenv,reyesyang/rbenv,josegonzalez/rbenv,cehoffman/nodenv,YanhaoYang/rbenv,zmwangx/pyenv,intfrr/rbenv,beck/rbenv,avdhoweb/rbenv,lozybean/pyenv,jrolfs/nodenv,jeongdeoksu/rbenv,royratcliffe/rbenv,nodenv/nodenv,janusnic/rbenv,skalee/rbenv,rridhan/rbenv,rinrinne/ndkenv,viclim/rbenv,jeongdeoksu/rbenv,hlecuanda/pyenv,raa0121/vimenv,viclim/rbenv,avdhoweb/rbenv,lozybean/pyenv,rowhit/pyenv,dark5un/nodenv,rbenv/rbenv,yyuu/pyenv,sheerun/rbenv,sstephenson/rbenv,jrolfs/nodenv,janusnic/rbenv,beck/rbenv,habinmusic/pyenv,Ferocia/rbenv,yogeshkakde/rbenv,reyesyang/rbenv,jpfuentes2/st2,lozybean/rbenv,xshwy/pyenv,rridhan/rbenv,reyesyang/rbenv,richo/rbenv,fly19890211/pyenv,bradynpoulsen/rbenv,doitian/rbenv,cehoffman/luaenv,UCASREN/pyenv,cehoffman/rbenv,stivenrgalvis/rbenv,dnsd/pyenv,yeonsh/pyenv,recruit-mtl/pyenv,mediadoneright/rbenv,silasb/rbenv,RinSer/rbenv,blueyed/rbenv,josegonzalez/rbenv,evertrue/rbenv,Ferocia/rbenv,cyril/rbenv,jmatbastos/rbenv,pumpkineater/rbenv,nodenv/nodenv,Angeldude/rbenv,stivenrgalvis/rbenv,cehoffman/rbenv,cehoffman/pyenv,codesdk/rbenv,RinSer/rbenv,codesdk/rbenv,lozybean/rbenv,zmwangx/pyenv,yyuu/rbenv,syndbg/goenv,ox/rbenv,jeremy/rbenv,syndbg/goenv,cyril/rbenv,chenfengyuan/pyenv,jmatbastos/rbenv,sstephenson/rbenv,intfrr/rbenv,jmatbastos/rbenv,jasonkarns/rbenv,jasonkarns/rbenv,BanzaiMan/pyenv,ffdc-scm/rbenv-x86_64-linux,jf/rbenv,jasonkarns/rbenv,yyyc514/rbenv,mediadoneright/rbenv,golib/goenv,cehoffman/nodenv,cehoffman/rbenv,pyenv/pyenv,andrew-christianson/rbenv,intfrr/rbenv,adarshmuthappa/nodenv,howtolearntocode/rbenv,yyyc514/rbenv,andrew-christianson/rbenv,talentdeficit/erlenv,yeonsh/pyenv,sodabrew/rbenv,Angeldude/rbenv,adarshmuthappa/nodenv,ffdc-scm/rbenv-x86_64-linux,jeongdeoksu/rbenv,docwhat/rbenv,yogeshkakde/rbenv,rbenv/rbenv,leocassarani/rbenv,xshwy/pyenv,cehoffman/pyenv,sebhahn/pyenv,pumpkineater/rbenv,LawnGnome/rbenv,ngyuki/phpenv,viclim/rbenv,ffdc-scm/rbenv-x86_64-linux,shoyan/rbenv,ffdc-scm/rbenv-x86_64-linux,nebhale/cfenv,avdhoweb/rbenv,cyril/rbenv,Ferocia/rbenv,princeofdarkness76/rbenv,jpfuentes2/st2,VShangxiao/pyenv,brntbeer/rbenv