This is done through the parser and so generates the same syntax error message if any parameters are wrongly specified for this event.
We were already enforcing event names in the parser.
This is only for state_entry so far as an initial test of the approach - appears to work correctly.
For loops with no assignment are no longer syntax errors. For example,
this is now valid:
for ( ; i < 10; i++) { ... }
Corresponding changes to lsl.{lexer,parser} in r99 in opensim-libs.
Fixes Mantis #2501. Fixes Mantis #2884.
