pass qgraph object rather than function

[vandenman]

Should fix the recurring network bug on windows.

[TimKDJ]

Fixes jasp-stats/jasp-issues#158, jasp-stats/jasp-issues#229, jasp-stats/jasp-issues#264 and possibly jasp-stats/jasp-issues#306

For future reference, the problem is as follows:
The network analysis plot is a qgraph object but we passed this to writeimage() as a function, which in turn transformed it to a recordedPlot and this recordedPlot was saved in the state. At the moment of retrieving this state the recordedPlot's complexity was apparently too great for R's load() and so R crashed. The condition was not caught by R and therefore the tryCatch() did nothing, which is why it appeared as a hard crash in JASP. To fix this we pass writeimage() the qgraph object and consequently this is also what goes in the state.

Not really sure what causes the difference between loading the state in the JASP context vs interactive R; or mac vs windows, but it appears solved now.