Flag floating point literals that have more digits than necessary

[dominikh]

For example,

x := 159.9999313354492045391452847979962825775146484375
y := 159.99993133544920453914528479799628257751464843749

and

x := 159.99993133544922
y := 159.9999313354492

are the same.

As usual, floating point numbers are crazy and I'm not sure that flagging these won't cause trouble in some bizarre edge case. Even if it doesn't, maybe it should only be a quickfix, so that people can copy & paste physical constants at very high precision without triggering an error.

Of course realistically, people should use constants for such numbers and it wouldn't make sense to flag uses of those constants, e.g. in x := math.Pi.