Rename this file for consistency.
Pick up formula expressions from ods.  Still work in progress.
Pass cached formula results & remove '=' from formula.

set_formula() interface expects formula expression without a '=' prefix.
Don't forget to return a real global settings instance here.
Document set_origin_date().
Prefix formula_grammar_t values with formula_grammar_.

Just to be consistent.
Use pimpl for import_factory.
Fix memory leak.  orcus_foo doesn't delete the factory instance.
No need to use boost::scoped_ptr for these.
import_factory to take a reference to the document instance.
Do the same with export_factory.
We don't need this now.
Allow app to set or get default formula grammar type.

This will be used when e.g. parsing range strings.
Move import_global_settings instance from document to factory.

Only used by the import filters.  Makes no sense to store it in the
document.
Adjust for change in ixion.

The document now stores formula name resolver instance which is responsible
for handling different reference types.
Set default grammar to ods at the beginning of load.
Provide a name resolver instance when setting formulas to ixion model.
This doesn't have to be created on the heap.
Restore the original grammar once the import is done.
Add skeleton ods session data.

This will be used to later store formula cell data.