Prevent cutoff in presence of iOS7 layout bug

[#62640192]
[#51993137]

Mobile Safari in iOS7 has layout issues. This at least prevents those issues from cutting off the submit button.

(Inconsistently, in order to make room for the browser's tab bar, Safari pushes absolutely positioned elements of the UI down 20px, or not, or doesn't push them down but makes them 20px too tall.)
Fix crashing null reference error in labels

[#62721794]
Revert "Refactoring magic number in graph padding (left)"

This reverts commit ba8fd8ff378be34f735486af0a75100ccb618cbc.

The refactoring created problems when a graph with an animation channel was re-rendered -- the left padding kept getting larger and larger.
Dismiss onscreen keyboard when 'enter' is pressed

[#62739922]