Renaming effSelector, effGroup, effLevel etc.?

effSelector, effGroup, effLevel and all different efficiency presentation types feel confusing - partially due to the names that are used. eff (efficiency) is certainly involved in the the conversion process, but it is not the most obvious name. Backbone equations that present the conversion are more aptly named 'q_conversion...'

We should try to select new names that would be more easy to understand for newcomers. Names can be suggested in the comments and the list below can be modified as needed.

• currently effSelector selects which conversion constraint is actually used for particular time (and particular section of the possible piece-wise linearization)
• conversionType could be a name for the set that defines possible ways to present the conversion process (effGroup is this now)
• effLevels are like the steps in a ladder - but what would be a good name: conversion...
• A complication is that lambda and incHR have index dimension in addition to the 'type'. This has been currently solved in a bit inelegant way where the indexes are also part of the 'type' set (effSelector).