general.debugcontext: filter out cmdlist and arglist
Core/Applets: log applet start/stop and duration
Core/ProcessManager: fix potential race-condition with $context object
Core/Interpreter:
* expand pronouns before command-substitution
* attempt to find current channel's factoid instance for metadata
* remove duplication of command history in command-substition
* terminate pipe/substitution processing when protecting self
Core/Factoids: limit -url contents to 250kb
"Applet" is a much better name for the external command-line
scripts and programs that can be loaded as PBot commands. They
will no longer be confused with Perl modules.
https://en.wikipedia.org/wiki/Applet
If ProcessManager::execute_process() returns undef,
then the loop in Interpreter::interpret() thinks that
the command didn't get handled, and so goes on to look
for other commands. This is now corrected.
