[Qt console] cannot insert new lines into console functions using tab

[satra]

OS X: 10.6

if you define a function on the console and come back to edit it, the indentation is off by one character when using tab. you can edit any existing line, but you cannot indent a new inserted line with a tab - seems to default to 3 spaces. if you physically type 4 spaces, its fine.

[takluyver]

On my system (Linux), the tab key seems to insert a tab character, rather than some spaces, when the cursor is at the beginning of a line.

[minrk]

I do not believe that tab gets converted into spaces in the console (it definitely doesn't on my OSX system). It is true that the result does not always align with 4-space indentation, but that's because the whole console is a rich text field, so the tab marks will actually vary relative to the line start depending on the length of the input prompt.

We should probably bind to insert 4 spaces, to prevent confusion.

[minrk]

Since the problem here is that tab inserts a tab character this isn't a bug, so I'm marking as an enhancement. We should definitely add support for soft-tabs, though.

[fperez]

See #900 for the tab-as-4-spaces issue.