Added Contact class that detects if a limb is on the ground

Signed-off-by: izzys <izzy.schall@gmail.com>
Contact object averages the force norm
changed treshold for contact detection
added IsStanding method
Changed CheckTippinjg contitions to include IsStanding, also changed RPY conditions

Signed-off-by: izzys <izzy.schall@gmail.com>
Merge branch 'Contacts' of https://github.com/EricSidorov/PW.git into TestSingles