**Steps to reproduce the problem**
- Define a contract template with one line with variable quantity and formula.
- Use that template in a new contract.
- Variable quantity type and formula are not transferred from template to contract.
This is due to the lack of that fields in the tree view that prevents web client to fetch
and store them.
We solve it adding those fields to the contract line tree view, also providing some
visibility logic for not showing the corresponding fields according the type.
No regression tests is provided, as this is only reproducible with web client, not through
code.
If you have contract lines with automatic price and your pricelist
contains different prices per quantity, the price is not changed
when computing quantity.
This PR fixes this.
