Sheet names starting with '.' or reading as R1C1 (R, C, RC, R1C1...) were saved
unquoted, so Excel could not open the file; PivotTable sources and ADDRESS left
cell-like names (A1) bare. The quoting rule, unquoting and sheet splitting now
live once in gridcraft_core::addr and replace the copies in the formula printer,
pivot, ADDRESS, chart, xlsx, Solver, Go To and the Name Box (which now reads ''
as ').
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
[@Col] is only Excel's display shorthand. Written verbatim into cell formulas and calculatedColumnFormula, it made Excel repair the file and drop the tables.
formula::parse("Sheet1!$D$1#") failed with "unknown error literal".
A # right after a cell reference is now the spill range operator: it
evaluates to the anchor's current spill range, or #REF! when the cell
doesn't spill (or its spill is blocked). Its users depend on the
anchor, so they recalculate when the spill grows or shrinks. Names can
use it.
Files have no # operator: like Excel, the writer stores A1# as
_xlfn.ANCHORARRAY(A1), and the parser reads that back as A1#.
