Adjustments to catalog display

[wendellpiez]

A few improvements to the NIST emulation presentation HTML XSLT:

• Top-level (table-driven configuration) for mapping part types to headers
  • Specifically, part[@class='guidance'] should be displayable as Discussion to match SP800-53 rev 5
  • But all part headers could be provided and configurable similarly
• Paragraph content of statements in Withdrawn controls should be italicized
  • Older data had <em> but this is semantically redundant - it does not capture emphasis, but only reflects the withdrawn state

[wendellpiez]

This work has been done.