* Moved getFieldInfo and getValue up right after related functions
* Modified getValue to return a valid status, so Lua can see if it got zero because of invalid source id
* Added new getSourceValue Lua function per Issue #781
Also added alias getSourceInfo for getFieldInfo
* Updated according to comment https://github.com/EdgeTX/edgetx/pull/2175#issuecomment-1245605114
* Replaced isFresh() by !isOld() as requested in https://github.com/EdgeTX/edgetx/pull/2316#issuecomment-1246759370
* Clean up `lua_pushtablenil` - tables cannot hold nil values
* Changed isFresh() to !isOld() ... AGAIN
* Return both `!isOld()` and `isFresh()`
* Return nil for all values if the item does not exist
* Return 0 instead of pushing three nil values
* Update documentation
