Calculate the unitised rate of return on a share portfolio.

This is a rough and ready script.  It (mostly) does what it is designed to do but there is nothing particularly elegant about it.

Files
ROR.py - The python script which calculates the account performance
MIDD.L.csv - An example file with the performance of an individual share.  This information, in the expected format, can be downloaded from yahoo finance.
account-transactions.csv - An example file with the transactions on the account listed

To Do
Move away from hard coded filenames and dates
Automate the maintenance of the account transaction csv file
Include stamp duty