Fixed really nasty bug

[neworderofjamie]

I have no idea WHY this was the behaviour but when you call a function from GeNN code e.g.

addSynapse(postInd,  flipKernRow, flipKernCol, preChan, kernOutChan);

in a Toeplitz connectivity initializer, if the first argument wasn't referenced in the function 'body' which gets substituted in (for example if the weight update model only calls addToPre which doesn't care about the postsynaptic neuron ID) then it gives up trying to substitute subsequent arguments.

Also, fixed a small bug relating to using addToPre with procedural connectivity (wrong environment was being used) and added some tests of addToPre with KERNEL weights

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.81%. Comparing base (80dc278) to head (081dac4).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #702      +/-   ##
==========================================
+ Coverage   88.75%   88.81%   +0.05%     
==========================================
  Files         106      106              
  Lines       14180    14180              
==========================================
+ Hits        12586    12594       +8     
+ Misses       1594     1586       -8     

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[tnowotny]

I see - nasty bug. Must have been a slip of attention at the time.
Fix seems straightforward.