...from mct-include. Improves behavior of that directive and supports
testing of changes to remove whole elements when inapplicable,
nasa/openmctweb#195.
Trust resource URLs to skip SCE-checking (which profiling
flags as a performance problem) for mct-include and
mct-representation; these URLs are pulled from bundles and
not user-entered, so should be trusted. WTD-1256.
Support priority ordering from the mct-include directive
(such that the highest-priority template for a given key
is what gets included.) Needed to support variations among
application logos in the bottom right (depending on deployment.)
WTD-667.
