modify caster to attempt to print better

modify caster to attempt to print better

* make ball smaller to grip better
* external perimeter speed up because slow speed caused bulging
* keep first layer speed slow so it adheres to print bed
* speed up gap fill speed. not sure what it does
* lower minimum print speed to accommodate slower speeds of other things
* speed up printing because slowness caused bulges
  * perimeter
  * small perimeter
  * solid infill
  * travel speed