[Bug] [BE] VarSQL variables will sometimes be overgeneralized into varlists

[colinthebomb1]

Issue

VarSQL variables will now sometimes be oversimplified into varlists. This issue is caused by PR #77 which prevents a possible infinite loop in rule generation.

Example

Previously the generated rule for ID 3 in the engine spreadsheet would be <x2> > <x3> AND <x2> <= <x3> but it is now <<y1>> > <x3> AND <<y1>> <= <x3>