Cleanup pass removing deprecated reactor-body APIs

[edwardalee]

This PR removes old, deprecated API macros originally used in early versions of the C runtime in reaction bodies. This enables substantial code simplification and clarification. Specifically, the following macros are removed:

• SET (use lf_set)
• SET_ARRAY (use malloc/calloc + lf_set_array)
• SET_NEW (use malloc/calloc + lf_set or lf_set_token)
• SET_NEW_ARRAY (use malloc/calloc + lf_set_array)
• SET_PRESENT (use lf_set_present)
• SET_TOKEN (use lf_set_token)
• SET_MODE (use lf_set_mode)

This PR also fixes a bug (see #352). A companion PR in lingua-franca updates tests that had been using the deprecated API.

Some API functions have also been removed:

• get_current_tag (use lf_tag)
• get_elapsed_physical_time (use lf_time_physical_elapsed)
• error_print_and_exit (use lf_print_error_and_exit)

[edwardalee]

This PR is ready for review. There is a companion PR in lingua-franca that requires a further companion review in the benchmarks repo in order to get all tests to pass.

[erlingrj]

This looks good, just some tiny comments

[lhstrh]

Since these are breaking changes, this suggests that the next version will be 1.0.0...