This requires splitting the `used` field into digital and analog components. The digital field stores the last-used timestamp, whereas the analog field stores the last value.
1) Add the "no-thrusters" ship flag to the list of flag that can be used by alter-ship-flag or the ship's setFlag function
2) Add a `FireRateMultiplier` virtvar to control the firing rate of turrets (fulfills #4300)
3) Add a `setGlowPointBankActive` function to do the same thing as `activate-glow-point-bank`/`deactivate-glow-point-bank`
It's not necessary here to assert on the correct variable type, as having the wrong type here won't cause the code to break. More importantly, the error will have been flagged before this point anyway, and this code is used for formatting the SEXP to be displayed in an error message. It's not helpful to pre-empt an error message with an assert.
Allow the variables controlling ship shudder to be independently set using scripting. Also add new flags to apply the shudder without decay and apply the shudder regardless of camera.
Also change the shudder timestamp to the new style.
* Add Animation Instance Flags
* Add SEXP barebones
* Unify and simplify animation parsing
* Clean up animation calling and use new animationlist api
* Add missing break
`Ai_flag_names[]`, `Object_flag_names[]`, and `Ship_flag_names[]` all had an associated `#define` containing their length that had to manually be incremented whenever new flag names were added to the list. This commit instead makes the number of flags in the list be computed by simple `sizeof` division, so now adding a new entry just requires adding the entry, rather than remembering to bump a `#define`. Tested in FRED to make sure populating `OPF_SHIP_FLAG` entries still works.
In #4443, `fl_near_zero` was set to use default epsilon values in the `IS_VEC_NULL` check. In this comparison, epsilon is the wrong threshold because it used to have a much smaller threshold. The fix restores the previous definitions of `IS_VEC_NULL` and `IS_VEC_NULL_SQ_SAFE` by exposing the epsilon value as an optional parameter (similar to how `IS_NEAR_ZERO` used to work. This PR also restores `IS_VEC_NULL_SQ_SAFE` where it was replaced by `IS_VEC_NULL.`
* more cleanup in preparation for model translation
1) Clean up stepped rotation, fixing some logic, adding safeguards for invalid values, and allowing rotations to go in the opposite direction
2) Add more specific SEXP error checking for AWACS and rotating subsystems
3) Assorted refactoring and polishing
* address feedback, plus a bit of extra cleanup
Sync the "mission save" and "error reporting" versions of the SEXP variable string. Also use `stuff_sexp_text_string` to print the "bad node" token rather than `Sexp_nodes[bad_node].text`, so that a human-readable token is displayed instead of a magic number like 26.
Related to #4226, as the generated error message is formatted differently enough to be confusing.
Another bug discovered by Durandal. The message sender was a variable containing an invalid value, and the game crashed. This handles it more gracefully.
Tested and verified.
The previous way to clear a skybox was to set it to "default", and if the mission had no skybox then it would be cleared. The skybox code can correctly handle the lack of a skybox, but if you pass an empty string to the skybox preloader it fails with a file not found error. This fixes the preloader, and also adds "none" as an explicit no-skybox parameter.
Goober5000