V0.1.8 staging - Githubissues

Minor updates and polish

Dates now render in the style of 2021-Jan-31 to be utterly unambiguous under review - can still be entered in ISO format
Default Form8949 display to be Cash Only instead of the prior combined cash and shares value
Added a per-lot post-merger tax basis column in addition to the per-share basis, in support of reporting 2023 post-merger sales
Support scenario where an ESPP lot is assigned to 100% cash - now includes the imputed income into the merger basis calculation
Add summary cell for post-merger average tax basis - this is needed for some non-US tax reporting
Added additional in-sheet doc notes for columns
Calculation and error handling changes - for neatness and unreachable edge case correctness, no impact on user values

Fixes #133 - sort of. The attached excel sheet is configured to support iterative calculations, and I've dropped the shared O365 one for now.

hickeng / financial