fix/improve field highlighting in reStructuredText
fix/improve field highlighting in reStructuredText

Swap order of field and role rules, as the latter was overriding the
former and causing it to never fire. Change field detection to a regex
with a stricter rule as to what comprises a "field" (specifically, to
prevent a role at the beginning of a line from being interpreted as a
field). Add support for inline markup in fields.

hlamer/kate,sandsmark/kate,sandsmark/kate,jfmcarreira/kate,hlamer/kate,jfmcarreira/kate,hlamer/kate,DickJ/kate,hlamer/kate,hlamer/kate,cmacq2/kate,hlamer/kate,hlamer/kate,sandsmark/kate,DickJ/kate,hlamer/kate,DickJ/kate,sandsmark/kate,cmacq2/kate,jfmcarreira/kate,DickJ/kate,hlamer/kate,cmacq2/kate,hlamer/kate