add working userloadfunc use example

[jorgepz]

check how is the user load func used in the static von mises problem

[TheChikenfly]

It seems the program never reads the userLoadsFilename function

[jorgepz]

indeed, there was an error in the boundarycons processing function https://github.com/ONSAS/ONSAS.m/pull/473/files#diff-7073a142f061a595b7f5ad33ffb4434bc30afd92995f861cc29fe3341fceaa7a

[jorgepz]

where the filename was loaded at not the first boundary cond it did not read it

[jorgepz]

I still have to fix the static von mises problem to add the user load filename case

[TheChikenfly]

I don't know if it helps but it seems to work if I use
boundaryConds(2).loadsTimeFact = @(t) myVMLoadFunc(t) ; boundaryConds(2).loadsBaseVals = [ 0 0 0 0 -1 0 ] ;
instead of boundaryConds(2).userLoadsFilename = 'myVMLoadFunc' ; in static von mises

[TheChikenfly]

(buut you have to change myVMLoadFunc so that the output is a scalar)

[jorgepz]

great, thanks with that. I think this issue will be left for after the Workshop.