incrparse: use python to diff rather than `diff`
incrparse: use python to diff rather than `diff`

Use the python library `difflib` which is part of a standard python
installation to generate the diff.  This allows us to run the tool on
Windows wihtout needing external tools installed.

apple/swift,ahoppen/swift,danielmartin/swift,harlanhaskins/swift,airspeedswift/swift,karwa/swift,stephentyrone/swift,lorentey/swift,hooman/swift,harlanhaskins/swift,stephentyrone/swift,aschwaighofer/swift,tkremenek/swift,austinzheng/swift,gregomni/swift,shahmishal/swift,practicalswift/swift,practicalswift/swift,benlangmuir/swift,gribozavr/swift,sschiau/swift,tkremenek/swift,parkera/swift,gribozavr/swift,JGiola/swift,airspeedswift/swift,ahoppen/swift,karwa/swift,karwa/swift,jckarter/swift,xedin/swift,devincoughlin/swift,parkera/swift,xedin/swift,roambotics/swift,rudkx/swift,shahmishal/swift,practicalswift/swift,jmgc/swift,aschwaighofer/swift,glessard/swift,lorentey/swift,hooman/swift,gregomni/swift,lorentey/swift,glessard/swift,atrick/swift,shahmishal/swift,airspeedswift/swift,stephentyrone/swift,gribozavr/swift,jckarter/swift,airspeedswift/swift,karwa/swift,harlanhaskins/swift,benlangmuir/swift,harlanhaskins/swift,rudkx/swift,shajrawi/swift,nathawes/swift,hooman/swift,shajrawi/swift,practicalswift/swift,benlangmuir/swift,lorentey/swift,gribozavr/swift,gregomni/swift,roambotics/swift,stephentyrone/swift,danielmartin/swift,sschiau/swift,allevato/swift,shahmishal/swift,karwa/swift,shajrawi/swift,allevato/swift,xedin/swift,amraboelela/swift,gregomni/swift,karwa/swift,rudkx/swift,airspeedswift/swift,nathawes/swift,aschwaighofer/swift,devincoughlin/swift,sschiau/swift,glessard/swift,tkremenek/swift,xedin/swift,gregomni/swift,atrick/swift,JGiola/swift,jmgc/swift,amraboelela/swift,JGiola/swift,nathawes/swift,nathawes/swift,rudkx/swift,practicalswift/swift,ahoppen/swift,airspeedswift/swift,roambotics/swift,roambotics/swift,sschiau/swift,jckarter/swift,gregomni/swift,practicalswift/swift,jckarter/swift,rudkx/swift,austinzheng/swift,ahoppen/swift,xwu/swift,austinzheng/swift,parkera/swift,shahmishal/swift,parkera/swift,practicalswift/swift,stephentyrone/swift,CodaFi/swift,amraboelela/swift,rudkx/swift,glessard/swift,hooman/swift,JGiola/swift,devincoughlin/swift,devincoughlin/swift,devincoughlin/swift,lorentey/swift,hooman/swift,austinzheng/swift,xwu/swift,jmgc/swift,karwa/swift,benlangmuir/swift,parkera/swift,atrick/swift,amraboelela/swift,gribozavr/swift,austinzheng/swift,gribozavr/swift,jckarter/swift,allevato/swift,devincoughlin/swift,jmgc/swift,hooman/swift,sschiau/swift,danielmartin/swift,tkremenek/swift,jmgc/swift,harlanhaskins/swift,lorentey/swift,roambotics/swift,stephentyrone/swift,allevato/swift,CodaFi/swift,allevato/swift,glessard/swift,gribozavr/swift,xwu/swift,CodaFi/swift,xwu/swift,shajrawi/swift,glessard/swift,aschwaighofer/swift,tkremenek/swift,shahmishal/swift,xwu/swift,CodaFi/swift,JGiola/swift,austinzheng/swift,ahoppen/swift,JGiola/swift,CodaFi/swift,aschwaighofer/swift,parkera/swift,sschiau/swift,harlanhaskins/swift,atrick/swift,tkremenek/swift,atrick/swift,austinzheng/swift,xwu/swift,apple/swift,xedin/swift,sschiau/swift,lorentey/swift,xedin/swift,nathawes/swift,xedin/swift,aschwaighofer/swift,amraboelela/swift,amraboelela/swift,xwu/swift,stephentyrone/swift,apple/swift,airspeedswift/swift,danielmartin/swift,harlanhaskins/swift,ahoppen/swift,hooman/swift,roambotics/swift,xedin/swift,shajrawi/swift,apple/swift,parkera/swift,nathawes/swift,devincoughlin/swift,CodaFi/swift,benlangmuir/swift,jckarter/swift,shahmishal/swift,nathawes/swift,CodaFi/swift,devincoughlin/swift,amraboelela/swift,shahmishal/swift,danielmartin/swift,apple/swift,jmgc/swift,jckarter/swift,practicalswift/swift,sschiau/swift,lorentey/swift,shajrawi/swift,jmgc/swift,apple/swift,benlangmuir/swift,karwa/swift,atrick/swift,allevato/swift,allevato/swift,tkremenek/swift,aschwaighofer/swift,parkera/swift,danielmartin/swift,shajrawi/swift,gribozavr/swift,danielmartin/swift,shajrawi/swift