Thread autoload bootstrap

[dktapps]

This is a duplicate of #23, which was closed by the deletion of the fork-ng branch and can't be reopened due to github.

Upon further musings, I think it would make sense to allow adding multiple files for this. In essence, this function allows the developer to say "require this file before running any thread code". Perhaps addAutoloadFile() instead of setAutoloadFile().

[dktapps]

In conjunction with Thread::getSharedGlobals(), this could become a powerful tool for thread bootstrapping

[dktapps]

Some new ideas:

• Allow providing parameters to the bootstrap script. This would be useful to make selected ThreadSafe objects automatically available to all threads (e.g. by putting them in static properties). This would probably be nicer than Thread::getSharedGlobals().
• Allow providing a Runnable instead of a file. File doesn't really make any sense and isn't consistent with anything else in the system.
• Allow providing multiple bootstraps (the current code only allows 1).

With the idea having occurred to me that bootstrap files could accept arguments, Thread::getSharedGlobals() suddenly makes a lot less sense...