Crash on budget creation when no income/expense account

[hsoft]

@@@
Application Identifier: com.hardcoded_software.moneyguru
Application Version: 1.6.2

Traceback (most recent call last):
File "/Applications/moneyGuru.app/Contents/Resources/mg_cocoa.plugin/Contents/Resources/mg_cocoa.py", line 550, in savePanel
File "moneyguru/gui/base.pyc", line 159, in save
File "moneyguru/gui/budget_panel.pyc", line 26, in _save
IndexError: list index out of range
@@@

[hsoft]

The crash is caused by by the lack of income/expense account during budget panel's save(). To reproduce:

1. Create a new document
2. Go to the budget view
3. Add a new budget
4. Press save (crash)

It shouldn't be possible to add a budget if the document doesn't have an income or expense account.

[hsoft]

[milestone:id#50408 bulk edit command]

[hsoft]

Fixed in [133]

[hsoft]

(from [133]) [#74 state:fixed] Prevent budgets from being added if there's no income/expense account.