Naming in Anomaly Cancellation for QED

[jstoobysmith]

In ./Odd/BasisLinear and ./Even/BasisLinear, there is a poor choice of variable names splitting the two planes.

An example in the odd case is:

physlib/Physlib/QFT/QED/AnomalyCancellation/Odd/BasisLinear.lean

Lines 282 to 291 in a6a22f9

	/-- The first part of the basis as charge assignments. -/
	def basisAsCharges (j : Fin n) : (PureU1 (2 * n + 1)).Charges :=
	fun i =>
	if i = oddFst j then
	1
	else
	if i = oddSnd j then
	- 1
	else
	0

compared to:

physlib/Physlib/QFT/QED/AnomalyCancellation/Odd/BasisLinear.lean

Lines 506 to 515 in a6a22f9

	/-- The second part of the basis as charge assignments. -/
	def basis!AsCharges (j : Fin n) : (PureU1 (2 * n + 1)).Charges :=
	fun i =>
	if i = oddShiftFst j then
	1
	else
	if i = oddShiftSnd j then
	- 1
	else
	0

There should be clearer descriptive naming around these planes. They should also be split into different file systems. The naming is tricky, but I think we should avoid something non-descriptive like plane1 etc.