Clarify `optimize4` method names: switch from `lowercase()` to `camelCase()`

Summary

optimize4 appears to introduce camelCase energy/constraint methods such as opt.addEnergy() and opt.addConstraint(), while the older optimize API uses lowercase methods like opt.addenergy() and opt.addconstraint().

Currently, both naming styles appear to work when importing optimize4, because both method variants are present. It would be helpful to clarify whether the lowercase methods are intentionally supported for backward compatibility, or whether users should migrate to the camelCase API.

Example

Using the older optimize style:

var opt = OptimizationProblem()
opt.addenergy(energy)

Using the new optimize4 style:

var opt = OptimizationProblem()
opt.addEnergy(energy)

Both currently seem to work. For example:

print opt.respondsto()

returns:

[
  addenergy,
  addconstraint,
  updateList,
  invoke,
  prnt,
  clss,
  has,
  setindex,
  clone,
  index,
  count,
  addLocalConstraint,
  addlocalconstraint,
  update,
  linearization,
  serialize,
  respondsto,
  init,
  superclass,
  enumerate,
  addEnergy,
  addConstraint
]

Is this intentional for backward compatibility? If so, should the docs mention that both are supported, and indicate which style is preferred going forward?

Start by checking how optimize4 exposes addenergy(), addconstraint(), addEnergy(), and addConstraint(), using the reported respondsto() output as the initial reference. Compare this with the older optimize API behavior. Done means the project clearly states whether the lowercase aliases are intentional, which spelling is preferred, and whether compatibility should be documented.