[TODO] Fix lathe calc

[gbowne1]

The lathe calc should:

• be accessible from the program list
• calculate material removal rate
• calculate chip load
• calculate spindle speed in rpm
• calculate feed rates
• calculate motor/spindle horsepower requirements
• calculate required feed per tooth
• calculate required depth of cut

Using standard machining formulas for turning metals.

In the current implementation the lathe app is duplicated twice and neither is accurate enough or contain the required elements for typical calculations required for lathe machining.