Calc functions and Calc option 'convert text to number'

Hi Eike,

I'm working on tdf64132, which is about SUM and text values that are not 
converted to numbers.

SUM uses ScInterpreter::IterateParameters(), which is used by various 
other Calc functions as well.

ScInterpreter::IterateParameters() does not handle the configuration 
settings for converting text to numbers properly.

For stack type svString I have a patch ready (gerrit #57346). The unit 
test is a problem for me, as the 'convert text to numbers' configuration 
is not in the test document and therefore unknown. This is illustrated 
by a test passing on my computer and failing for Jenkins.

But the larger challenge lies with stack type svDoubleRef (probably the 
most used one). Here a sc::ColumnSpanSet is used with 
sc::ColumnSpanSet::ColumnAction (a.o. FuncSum), which in turn uses 
NumericCellAccumulator. And that class handles only 
sc::element_type_numeric and sc::element_type_formula, so text is 
discarded. I could add sc::element_type_string and the conversion to 
numbers depending on the configuration settings.

As that will have consequences beyond the Calc functions SUM and the 
like, I would like you opinion on this before I start implementing.

And all this leads to the question if all Calc functions expecting 
numeric arguments handle the 'convert text to numbers' configuration as 
advertised. It looks like I can keep myself occupied for quite some time 
with this ;-)

Winfried