Fix typos, update constructors, add Chambolle-Pock constructor

[lostella]

cc @pylat

Main changes:

• raise an error in case Lipschitz constants are not given (but the corresponding terms are)
• add constructor for Chambolle-Pock (it's a very famous algorithm, there should be a direct way to instantiate it, even if it’s just a special case of Vu-Condat)
• refactor a little the default stepsize computation
• fix typos in the docstrings

[codecov]

Codecov Report

Merging #61 (0fd3ad2) into master (ee31033) will decrease coverage by 0.05%.
The diff coverage is 48.57%.

@@            Coverage Diff             @@
##           master      #61      +/-   ##
==========================================
- Coverage   89.39%   89.33%   -0.06%     
==========================================
  Files          22       22              
  Lines         962      966       +4     
==========================================
+ Hits          860      863       +3     
- Misses        102      103       +1     

Impacted Files	Coverage Δ
src/algorithms/primal_dual.jl	63.93% <48.57%> (+0.37%)	⬆️

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[lostella]

@pylat do you have any concern with this? If not, I’ll merge it and move on with other changes I have in the pipeline

[lostella]

(Merging: I will address any comment or concern later on)