Only handle and fire mousemove events when the user's either dragging or moving the mouse within the view.
Only handle and fire mousemove events when the user's either dragging or moving the mouse within the view.

Fixes #352.

Olegas/paper.js,proofme/paper.js,ClaireRutkoske/paper.js,iconexperience/paper.js,superjudge/paper.js,legendvijay/paper.js,baiyanghese/paper.js,rgordeev/paper.js,li0t/paper.js,byte-foundry/paper.js,nancymark/paper.js,EskenderDev/paper.js,baiyanghese/paper.js,mcanthony/paper.js,fredoche/paper.js,rgordeev/paper.js,lehni/paper.js,rgordeev/paper.js,baiyanghese/paper.js,JunaidPaul/paper.js,li0t/paper.js,Olegas/paper.js,mcanthony/paper.js,nancymark/paper.js,ClaireRutkoske/paper.js,mcanthony/paper.js,lehni/paper.js,byte-foundry/paper.js,EskenderDev/paper.js,nancymark/paper.js,iconexperience/paper.js,proofme/paper.js,legendvijay/paper.js,fredoche/paper.js,chad-autry/paper.js,luisbrito/paper.js,iconexperience/paper.js,JunaidPaul/paper.js,fredoche/paper.js,lehni/paper.js,superjudge/paper.js,legendvijay/paper.js,EskenderDev/paper.js,JunaidPaul/paper.js,superjudge/paper.js,luisbrito/paper.js,li0t/paper.js,ClaireRutkoske/paper.js,Olegas/paper.js,luisbrito/paper.js,byte-foundry/paper.js,proofme/paper.js