implement more initial coordinate options for layouts

[skyebend]

(migrated from statnet trac ticket #19)

many layouts need (and results are influenced by) the set of initial seed coordinates fed into the layout process. Currently only option is random, or explicitly setting seed coords. probably should add circle or other layout functions

Changed 3 years ago by skyebend this should also control the initial positions of newly entering vertices as they are 'born'

comment:3 Changed 2 years ago by skyebend [12450/statnet_commons] Added new argument to render.animation's render.par: initial.coord which will be internally formed into a matrix of default coordinates. partially addresses this issue.