enum for interaction types allowed in PV

[mkutmon]

Line
Arrow
TBar
mim-necessary-stimulation
mim-binding
mim-conversion
mim-stimulation
mim-catalysis
mim-modification
mim-inhibition
mim-covalent-bond
mim-transcription-translation

[saurabhkumar13]

these are for Point@arrowHead yes?