added plotmetadata attribute to functionnode
Add method to PlotWidget to plot function
Add method to PlotWidget to plot a FunctionNode
Add math.js library to support functions
Merge branch 'development' into plotmetadata2functionnode
changed comment to pass doc generation
Merge pull request #213 from openworm/plotmetadata2functionnode

Plotmetadata2functionnode
Merge branch 'development' into events