Changed page delimiter to ----+

See issue #167
Changed page break style in www/*
Replaced all page breaks in doc/*
Updated test_json_resource
Updated test_resources.py, EXCEPT for negotiated resources
Updated test_website
Initial implementation of issue #167

-Untested
-Other source files have not been updated
Updated most of the page breaks
Fixed most of the remaining page breaks
Add long id to security.txt, per @dstufft
Fixed split not yielding the final page
Removed redundant assertion from RenderedResource
Line offsets are now calculated during page splitting
Updated test_resources for padding/offset change
Fixed very obvious typo
Offset now calculates based on all previous pages

Previously, it incorrectly only used the one previous page
Renamed test_offsets to check_offsets
Updated some negotiated_resource tests
Undid accidental change to Makefile
Added (unfinished) test suite for the generic functions in resources