Remove the "Special Technical Topics" section from the "Advanced Topics Documentation"

[jagerber48]

For 4.0.0 release I am looking through the documentation. I think we can remove the "Special Technical Topics" of the "Advanced Topics" page of the documentation. This leaves the "API" section. I think the "API" section should be kept and that it can be improved.

The Special Technical Topics is almost a compendium of all of the strange behaviors of uncertainties < 4.0 which are going to be resolved by 4.0.

• Pickling: under the new architecture the immutable UFloat objects can be pickled and unpickled. Since the old behavior was, in my opinion, strange, we can include a note in the documentation clarifying the change in behavior, but this short note can be moved to the user guide.
• Comparison operators: The old behavior was confusing. Now we are removing the confusing comparison operators.
• Linear Propagation of uncertainties: This section can be in the user guide
• NaN uncertainty: this was tied up in the zero std_dev handling discussion. Basically this section was an attempt at supporting some of the strange edge cases, but as was discovered in other threads, some weird edge cases still remained. The behavior will be a bit different in 4.0, but, more importantly, we've decided we don't want to support these kind of edge cases, so we can just drop this documentation.
• Mathematical definition of numbers with uncertainties: This gets folded into the User Guide when discussing how a UFloat is like a random variable.
• Differentiation method: It is worth mentioning that uncertainties uses analytic derivatives where possible, and numerical derivatives elsewhere. But, 4.x drop some of the ability for users to access the derivatives of expressions so less words need to be spent here. Can be in user guide
• Tracking of random variables: This section seems to be mostly about mutating UFloat objects, something that is not allowed in 4.x.
• Python classes for variables and functions with uncertainty: This is exactly the core thing that is changed by 4.x

So my plan is to just delete many of these section and, otherwise, fold them into existing or new sections in the user guide.

[wshanks]

This plan sounds good to me.