Fix dodge.width default

[csdaw]

Hi Erik, apologies I haven't been able to help with this package as much as before (4th year PhD is busy surprisingly 😆 )

This small PR does the following:

• In quasirandom functions, change dodge.width default to NULL instead of 0 (fixes Quasirandom behaves differently after update to 0.7.1 #79)
• Removes a few stray references to deprecated groupOnX in the README and vignette
• Increments the package version from 0.7.1 to 0.7.1.9000
• Updates NEWS.md with the above notes

[eclarke]

Excellent, thank you @csdaw- your help is always appreciated, especially with how crazy the last year or two of a PhD can be!