Fixes: the Expenses page, and the earnings menu that did nothing

A round-up of what was broken and now is not.

• The Expenses page would not open. It showed "Something went wrong" for any account with an expense logged. Two faults, both from shared code that moved while the phone app was being built. Nothing was lost while it was down: every expense was still there, and the page shows them again.
• The earnings view menu changed nothing. Picking a platform or your other income saved the choice and left every figure on the page exactly as it was. It now narrows the figures properly, and the tax is worked out again over what is left rather than sliced up afterwards.
• The PAYE tax figure was thrown away. Tax already deducted was collected on the form, added up, and then left out of the calculation. It is credited against the bill now.
• Class 4 National Insurance was charged on wages. It is a charge on trading profit, so a job no longer pulls your driving profit into it, while the wages still use up the personal allowance and the bands.
• A duplicate deadline. "Tell HMRC you are self-employed" appeared several times over on the deadlines list, once per carried-over year, all on the same date.
• Three settings that did nothing on the website. Vibration, shift sounds and filling in postcodes from your location only work on a phone, so the website no longer shows switches for them. Whatever you set in the app stays set.

If you hit the Expenses page fault, there is nothing you need to do. Reload it and your entries and totals are as they were.