df#50950 sort out Calc (ISO)WEEKNUM functions

[Winfried Donkers]

Hi Eike,


> I'm a bit lost here. Maybe we need to sort that out from scratch again.
> This appears to be the most complicated change in function names we're
> tackling because of the different functions AND having an Add-In function
> involved AND different names for similar but not quite identical functions
> in UI and file formats.
> 
> Let's postpone until April ...

It's April, the sun is up :)

I'll try to explain the situation as I see it.

As you know, the problem is that the ODFF function name ISOWEEKNUM is currently used for a function with WEEKNUM functionality.

I checked the function definitions for WEEKNUM and ISOWEEKNUM, for ODFF and Excel. ODFF and Excel are as good as identical, except that Excel may experience problems when the date value is entered is text.
I intend to ignore that difference and support both WEEKNUM and ISOWEEKNUM in Calc.

I propose to put right in 2 steps.
UI: 			English function name used in user interface
ODFF: 		function name used in ODFF-document (ods)
ODFF-legacy:	function name that can be read from ODFF-document and will be converted to ODFF function name; used for backwards compatibility (conversion in ScCompiler::IsOpCode())
EXcel:		function name used for export/import to/from Excel (xlsx)

LO version 4.5:
UI		ODFF			ODFF-'legacy'		Excel
WEEKNUM	WEEKNUM		ISOWEEKNUM			WEEKNUM
ISOWEEKNUM	ISOWEEKNUM_TMP					ISOWEEKNUM
remove UI WEEKNUM_ADD (similar as with GCD_ADD, gerrit#15185)

LO version 4.6:
UI		ODFF			ODFF-'legacy'		Excel
WEEKNUM	WEEKNUM						WEEKNUM
ISOWEEKNUM	ISOWEEKNUM		ISOWEEKNUM_TMP		ISOWEEKNUM

Any questions, objections, suggestions?

Winfried