v1.3.1 readme: better handling of non-standard datatypes
v1.3.1 readme: better handling of non-standard datatypes

jlukanta/mixpanel-iphone,jlukanta/mixpanel-iphone,orta/mixpanel-osx-unofficial,jlukanta/mixpanel-iphone,tisohjung/mixpanel-iphone,bloom/mixpanel-osx-unofficial,mman/mixpanel-osx-unofficial,vojto/amplitude-osx,senselabs/mixpanel-iphone,senselabs/mixpanel-iphone,senselabs/mixpanel-iphone,mman/mixpanel-osx-unofficial,senselabs/mixpanel-iphone,orta/mixpanel-osx-unofficial,senselabs/mixpanel-iphone,senselabs/mixpanel-iphone