Tweak ideas for block syntax sugar.
Add File size method.
Add Ruby-style "do" blocks.

- No non-local returns yet.
- No arguments yet.
Add parameter patterns to block arguments.
Add File open() method that takes a block.
File read method!
Get rid of old Suspension stuff.
File read(path) method.
Remove some outdated TODOs. They're TODONE!
Require imports to appear first in a module.
Add Iterable join() method.
Iterable contains() method.