locality and docs for generate Beehive

[dehann]

Still problems with some of the landmarks not showing up? Not sure why that is, but will fix along with regular upgrading of RoME to new Manifolds approach to factors.

Locality parameter was suggested by @Affie

using RoME, Cairo, RoMEPlotting

fg = generateCanonicalFG_Beehive!(100, graphinit=false, locality=2)
plotSLAM2D(fg, solveKey=:simulated, drawPoints=false, drawEllipse=false, drawContour=false)