Harmonize UI when editing events

[LaChope]

The merge of #396 and #367 led to inconsistent UI when editing nodes.

• @Kasmadei For basic nodes, there are now 2 ways to edit the failure rate (we want only the radio, not input field) (also described in Manually defined failure rate for BASIC node #451)
• @LaChope The save button should be after the radio options (right now it is in between failure rate field and radio options)
• @LaChope Open for discussion, but the "Description" field does not look nice at all to me

@blcham

[Kasmadei]

First point: #463

[blcham]

Current state:

[grotskat]

@blcham

• Root node

• 2x Event name

• the separator is between failure rates (Is that right?)

• after changing the Gate type, the SAVE button is under failure rates (Is that right?)

[blcham]

We agreed to:

• have the SAVE/DISCARD button right above the separator, which is right below failure rates.
• have separator below MOH

[grotskat]

It works.