Add macros to syntax highlighting

[lucaswerkmeister]

It would be nice if this mode supported syntax highlighting for gnuplot macros (@variable). (Does that belong in the syntax table or in the Font Lock defaults?)

Thanks for writing this mode, by the way, it’s makes it much more pleasant to edit gnuplot code :)

[lucaswerkmeister]

font-lock-preprocessor-face sounds like the right Font Lock face to use.