$ is invalid in C identifiers

[Martin Sjölund]

The current C-code still uses dollars in identifiers in order to generate code despite being invalid in C.

avr-gcc does not like it, and -fdollars-in-identifiers can be used to pass the pre-processor. But the linker cannot handle dollars as symbol names, so we should try to remove the remaining uses of dollar-signs if possible (avr-gcc might be able to compile code anyway since I think we mostly use $ in preprocessor names, but if they appear in functions we need to fix those).

[Martin Sjölund]

We should possibly add -fno-dollars-in-identifiers to the flags passed to the CC when building the code.