Unify interface for linesearches

[anriseth]

Fixes #118 and #119

[codecov]

Codecov Report

Merging #121 into master will decrease coverage by 0.31%.
The diff coverage is 42.85%.

@@            Coverage Diff            @@
##           master    #121      +/-   ##
=========================================
- Coverage   60.62%   60.3%   -0.32%     
=========================================
  Files           8       8              
  Lines         645     650       +5     
=========================================
+ Hits          391     392       +1     
- Misses        254     258       +4

Impacted Files	Coverage Δ
src/morethuente.jl	54.78% <0%> (-0.3%)	⬇️
src/hagerzhang.jl	52.19% <0%> (-0.23%)	⬇️
src/backtracking.jl	82.05% <100%> (+0.47%)	⬆️
src/static.jl	32.35% <33.33%> (-2.03%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2119606...c4fff26. Read the comment docs.