Add column to AccountListView showing shares bought/sold

Issue: #83
Add purchase price to buy/sell transactions in account

Issue: #83
CrossEntry: add method to retrieve owner of transaction
Add portfolio and account to security performance view

Issue: #81
Add column showing portfolio and account of transaction

Issue: #81
Avoid pre-selection of account/portfolio when not known

The buy/sell/dividends dialog should not preselect the first account or
portfolio when opening the dialog as it leads to easy erroneous entries.
Preselect only if just one account or portfolio exist.

Issue: #82
Merge pull request #89 from simpsus/feature_sparplan

Simplifying InvestmentPlans
Improvements to investment plan

* Re-enable loading column configuration
* Right-align numeric columns
* Context-menu: delete investment plan
* Auto pack columns only if not configured by user
* Remove transactions from plan if deleted in other views
* Use translated labels which already exist
* Align plan attributes so that dialog and list use same order
Merge branch 'feature_sparplan'
Extract common portfolio transaction viewer

Used in PortfolioListView as well as InvestmentPlanListView
Add interval to investment plan (plus fixes)

* add interval to create transactions monthly or every x months
* ensure day of month is always the same (even if end of month)
* rename transaction costs to fees
Delete investment plan when deleting associated portfolio and account
Add icon for investment plan
Translate investment plan labels
Performance chart: add security as benchmark *and* performance series

Issue: #85