Levelmeter: Ensure that variables and png names (roughly) match

[hoffie]

From #2356 (comment):

E.g.
BitmCubeRoundBigLedBlack ( QString::fromUtf8 ( ":/png/LEDs/res/CLEDBlackSmall.png" ) ),

It's a bit surprising to see "Big" being mapped to "Small" here.

[ann0see]

@henkdegroot do you plan to fix this?

[henkdegroot]

I notice a few issues related to meterstyle, so perhaps include all in one PR?

[ann0see]

Yes you can but please split commits

[henkdegroot]

As you can see from the PR, I did a separate one for this.