engine/rule_logger: Strip whitespace.
engine/rule_logger.c: Indentation cleanup.
predicate: Spell check.
core: Fixing incorrect range check for HTTP error status codes.
var: both result and mp should be null when calling b_var_target_remove() and ENOENT is OK when removing a value.
rule_engine: Expressing error pages in terms of a callback function.
error_page: Implementing error page module.

This module will use the error page callback functions to provide
custom error pages per-status code per site.
error_page: Unit tests.
error_page: Portably print a 64 bit value.
engine/core_vars.c, modules/fast.c: No longer set placeholder values in vars. (RNS-621)
acinclude/ax_boost_suffix.m4: Improve error message when boost location not known.