[MRG] add is_lineage_match, pop_to_rank, make_lineage to lca_utils

[ctb]

Add some useful functions to sourmash.lca.lca_utils. Right now they're mostly used in charcoal.

Fixes #458

• Is it mergeable?
• make test Did it pass the tests?
• make coverage Is the new code covered?
• Did it change the command-line interface? Only additions are allowed
  without a major version increment. Changing file formats also requires a
  major version number increment.
• Was a spellchecker run on the source code and documentation after
  changes were made?

[codecov]

Codecov Report

Merging #1081 into master will increase coverage by 9.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1081      +/-   ##
==========================================
+ Coverage   83.77%   92.81%   +9.03%     
==========================================
  Files          99       74      -25     
  Lines        8958     5692    -3266     
==========================================
- Hits         7505     5283    -2222     
+ Misses       1453      409    -1044     

Flag	Coverage Δ
#rusttests	?

Impacted Files	Coverage Δ
sourmash/lca/lca_utils.py	92.80% <100.00%> (-3.04%)	⬇️
src/core/src/signature.rs
src/core/src/sketch/ukhs.rs
src/core/src/sketch/minhash.rs
src/core/src/wasm.rs
src/core/src/cmd.rs
src/core/src/errors.rs
src/core/src/ffi/utils.rs
src/core/src/ffi/cmd/compute.rs
... and 17 more

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[ctb]

ready for review & merge @erikyoung85 @bluegenes

[bluegenes]

lgtm!