add a few type checks to limit type to SomeInteger
add a few type checks to limit type to SomeInteger

(adding a compund type to the Rational type definition
made it too difficult to define new variables
using integer literals)

jsanjuas/Nim,singularperturbation/Nim,sarvex/Nim-lang,jfhg/Nim,russpowers/Nim,endragor/Nim,jsanjuas/Nim,endragor/Nim,zachaysan/Nim,jfhg/Nim,russpowers/Nim,singularperturbation/Nim,endragor/Nim,msmith491/Nim,zachaysan/Nim,jfhg/Nim,sarvex/Nim-lang,dom96/Nim,haiodo/Nim,Dhertz/Nim,tulayang/Nim,nanoant/Nim,tulayang/Nim,zachaysan/Nim,nanoant/Nim,haiodo/Nim,singularperturbation/Nim,russpowers/Nim,jfhg/Nim,msmith491/Nim,mbaulch/Nim,msmith491/Nim,sarvex/Nim-lang,tulayang/Nim,Dhertz/Nim,haiodo/Nim,dom96/Nim,Matt14916/Nim,nanoant/Nim,russpowers/Nim,sarvex/Nim-lang,dom96/Nim,Dhertz/Nim,dom96/Nim,msmith491/Nim,jsanjuas/Nim,singularperturbation/Nim,msmith491/Nim,jsanjuas/Nim,singularperturbation/Nim,singularperturbation/Nim,mbaulch/Nim,nanoant/Nim,sarvex/Nim-lang,Matt14916/Nim,russpowers/Nim,jfhg/Nim,tulayang/Nim,haiodo/Nim,dom96/Nim,haiodo/Nim,nanoant/Nim,jsanjuas/Nim,russpowers/Nim,singularperturbation/Nim,sarvex/Nim-lang,msmith491/Nim,jfhg/Nim,haiodo/Nim,Matt14916/Nim,haiodo/Nim,mbaulch/Nim,Dhertz/Nim,Matt14916/Nim,zachaysan/Nim,dom96/Nim,Matt14916/Nim,zachaysan/Nim,nanoant/Nim,mbaulch/Nim,tulayang/Nim,mbaulch/Nim,jsanjuas/Nim,jfhg/Nim,Dhertz/Nim,russpowers/Nim,nanoant/Nim,endragor/Nim,zachaysan/Nim,Matt14916/Nim,mbaulch/Nim,endragor/Nim,sarvex/Nim-lang,jsanjuas/Nim,Dhertz/Nim,endragor/Nim,zachaysan/Nim,msmith491/Nim,Dhertz/Nim,tulayang/Nim,mbaulch/Nim,endragor/Nim,Matt14916/Nim,dom96/Nim