Modification of difficulty and score scaling #21
Description
Add modular difficulty settings such as:
- speed - speed of ships as well as spawn rate (slider from perhaps 1/5 -> 2x speed)
- problem types - have each own their independent point values as well as contributing to the overall scale for their combination
- no bonus ships mode
- no bosses
- waves vs endless
- number of bases (1 to maybe 8?)
- no healing