Add guidance to questions

[florianm]

Would it be feasible to add "guidance" to fields?

Most help text I'm showing as hints would be far better off as "guidance" with the option to collapse and thus make the form more compact for experienced enumerators, while allowing to include sufficient help text to enumerators in training.

Found in XForms spec:

<text id="how-old-label">
    <value>How old are you?</value>
    <value form="short">Age</value>
</text>
<text id="how-old-hint">
    <value>Enter a number</value>
    <value form="guidance">If the age is less than 18, the remainder of the survey will be hidden.</value>
</text>

Possible implementation:
ODK Build could offer a field "guidance" after the field "hint" input which adds the guidance as <value form="guidance"...</value> to the respective <text id="...:hint"> nodes.
And while we're there, support for a short label might be very similar to add.

A hack for now:

• Append the guidance text to the text in hint, separated by a string like GUIDANCE.
• Export to XML.
• Edit XML, search-replace all occurrences of GUIDANCE with </value><value form="guidance">.
• Publish form e.g. through ODK Central.

[florianm]

Closing as duplicate of #242