UPDATE: Implement the implicit Intersection Operator

The II operator takes a range and returns a single cell that is in the same column or the same row
as the present cell.

This is needed for backwards compatibility with old Excel models and as a first step towards dynamic arrays.

In the past Excel would evaluate `=A1:A10` in cell `C3` as `A3`, but today in results in an array containing all
values in the range. To be compatible with old workbooks Excel inserts the II operator
on those cases.

So this PR performs an static analysis on all formulas inserting on import automatically the II operator
where necessary. This we call the _automatic implicit operator_. When exporting to Excel the operator is striped away.
You can also manually use the II. For instance `=SUM(@A1:A10)` in cell `C3`.
This was not possible before and such a formula would break backwards compatibility with Excel. To Excel that "non automatic"
form of the II is exported as `_xlfn.SINGLE()`.

Th static analysis has to be done for all arithmetic operations and all functions.
This is a bit of a daunting task and it is not done fully in this PR. We also need to implement arrays and dynamic arrays.
My believe is that once the core operations have been implemented we can go formula by formula writing proper tests and documentation.

After this PR formulas like `=A1:A10` for instance will return `#N/IMPL!` instead of performing the implicit intersection

base/src/test/mod.rs

@@ -28,7 +28,6 @@ mod test_fn_sumifs;
 mod test_fn_textbefore;
 mod test_fn_textjoin;
 mod test_fn_unicode;
-mod test_forward_references;
 mod test_frozen_rows_columns;
 mod test_general;
 mod test_math;
@@ -59,6 +58,7 @@ mod test_fn_type;
 mod test_frozen_rows_and_columns;
 mod test_geomean;
 mod test_get_cell_content;
+mod test_implicit_intersection;
 mod test_issue_155;
 mod test_percentage;
 mod test_set_functions_error_handling;