adding Krylov package to repo

.gitignore

Krylov.jl/.cirrus.yml

Krylov.jl/.github/workflows/CompatHelper.yml

Krylov.jl/.github/workflows/TagBot.yml

Krylov.jl/.gitignore

Krylov.jl/.travis.yml

Krylov.jl/.zenodo.json

Krylov.jl/LICENSE.md

Krylov.jl/Project.toml

Krylov.jl/README.md

Krylov.jl/appveyor.yml

Krylov.jl/benchmark/REQUIRE

Krylov.jl/benchmark/benchmarks.jl

Krylov.jl/benchmark/cg_bmark.jl

Krylov.jl/benchmark/run_benchmarks.jl

Krylov.jl/benchmark/solver_benchmark.jl

Krylov.jl/docs/Project.toml

Krylov.jl/docs/make.jl

Krylov.jl/docs/src/api.md

Krylov.jl/docs/src/assets/logo.png