improve boat speed checks

[adampoulson]

added speed check for water and ground and fixed some false positives about boats. fixes #134

[Lysandr0]

Sorry for the really late response. Going to leave this one to Xaw3ep because vehicles are kind of junk in recent Minecraft versions and I'm unsure whether they plan on doing something specifically. :p

[xaw3ep]

Less work, less distraction. Thank you very much