Respect leading comments (e.g. encoding)

Switches ExpressionList from tracking line numbers across calls to
tracking just the offset for the current invocation to call.
respect leading =begin/=end
Run programs from cwd instead of the dir of the file being evaluated
The binary now gets the result instead of the printer
Refactor: switch ivar getting reset on each call to ExpressionList#call to a local variable
Refactor: remove invocation order coupling

Used to have to call printer before could call results
Add more examples (multiple levels of nesting) to the basic functionality cuke
Move the files that only have to do with the binary into a subdir
Bump version to 0.0.10