define mul! for quasi-Newton operators

[dpo]

Fixes #154

[codecov]

Codecov Report

Merging #170 (f20acb0) into master (2384869) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #170      +/-   ##
==========================================
+ Coverage   96.92%   96.95%   +0.03%     
==========================================
  Files          14       14              
  Lines         748      756       +8     
==========================================
+ Hits          725      733       +8     
  Misses         23       23              

Impacted Files	Coverage Δ
src/lbfgs.jl	97.58% <100.00%> (+0.08%)	⬆️
src/lsr1.jl	98.90% <100.00%> (+0.05%)	⬆️

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[github-actions]

Package name	latest	stable
CaNNOLeS.jl
DCI.jl
JSOSolvers.jl
Krylov.jl
NLPModels.jl
NLPModelsModifiers.jl
Percival.jl
QuadraticModels.jl
SolverTools.jl

[dpo]

We still support Julia 1.0 in our Project.toml and I think things work with 1.0 but

1. we're not testing it with Github Actions;
2. Arpack (that I'm now using in the tests) fails to install with Julia 1.0 (at least on FreeBSD).

Should we require Julia 1.3?

[abelsiqueira]

We still support Julia 1.0 in our Project.toml and I think things work with 1.0 but

1. we're not testing it with Github Actions;
2. Arpack (that I'm now using in the tests) fails to install with Julia 1.0 (at least on FreeBSD).

Should we require Julia 1.3?

I think it's safe to drop 1.0.

[github-actions]

Package name	latest	stable
CaNNOLeS.jl
DCI.jl
JSOSolvers.jl
Krylov.jl
NLPModels.jl
NLPModelsModifiers.jl
Percival.jl
QuadraticModels.jl
SolverTools.jl

[github-actions]

Package name	latest	stable
CaNNOLeS.jl
DCI.jl
JSOSolvers.jl
Krylov.jl
NLPModels.jl
NLPModelsModifiers.jl
Percival.jl
QuadraticModels.jl
SolverTools.jl

[github-actions]

Package name	latest	stable
CaNNOLeS.jl
DCI.jl
JSOSolvers.jl
Krylov.jl
NLPModels.jl
NLPModelsModifiers.jl
Percival.jl
QuadraticModels.jl
SolverTools.jl

[github-actions]

Package name	latest	stable
CaNNOLeS.jl
DCI.jl
JSOSolvers.jl
Krylov.jl
NLPModels.jl
NLPModelsModifiers.jl
Percival.jl
QuadraticModels.jl
SolverTools.jl