Servo Block. Permit different servo types

Servo 'attach' with matching specifications to achieve 180 degree rotation.

More gracefully insist that 'pin number' must be a constant.

Includes new 'number-const' GenusType that uses 'number-list' connector.
Merge pull request #62 from TonyCallear/SERVO-TC-v2

Improve Servo Block: Permit different servo types ( extra parameters to 'attach' call )
add bin/ to gitignore file
Merge branch 'master' of github.com:taweili/ardublock
Merge remote-tracking branch 'upstream/master'