Removes everything between $ontext and $offtext, inclusive.
Details
Exported because consumers that parse GAMS sources of their own - energyRt's model code, for one - need the same treatment before scanning for domain hints, and duplicating it would let the two drift.
Examples
remove_ontext_offtext(c("a;", "$ontext", "note", "$offtext", "b;"))
#> [1] "a;" "b;"
