ENH: Rework Single Point Jobs

[HaoZeke]

Bit of scope creep, but basically:

• Updates / refactors out the Parameters
  • Instead of passing a giant (often unused) structure, we now have separate configurations per job / section
• Makes ownership semantics trivial to note
  • I think we will see very little heap allocation, most of the jobs know upfront how many objects are to be created, i.e. stack allocation should be good enough, maybe a few reference_wrapper objects
• Most Potentials have parameters either hardcoded / or stored in a slightly unintuitive way under Parameters, and they don't require them for construction anyway, the factory functions have been updated as well
• Better performance and less bugs, by virtue of more enum class and stronger type system use

Most of these don't require any changes at all to the server other than the rather obvious TOML migration issue.

[HaoZeke]

OK so this is getting out of hand, so it is being merged with:

• The single point job correctly using the new stack based approach with the parameters
• Adds namespaces
• Refactored out the element handling into its own thing (with tests)

Subsequent PRs will refine this and add back more functionality.

[HaoZeke]

These are roughly at the same speed as the eOn SVN branch.

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
eonclient -s client/example/pos.con -p lj	11.1 ± 2.0	5.5	15.8	1.00
eonSVNonly/client/eonclient -s client/example/pos.con -p lj	11.8 ± 2.3	4.8	23.5	1.06 ± 0.28

[HaoZeke]

Ergo, this is being merged in for now. Much cleaner.