Add tree sequence metadata and schema to low-level python

[benjeffery]

Low-level python part of #534, stacked on #642

• TableCollection properties
• TreeSequence properties

[codecov]

Codecov Report

Merging #644 into master will decrease coverage by 0.02%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##           master     #644      +/-   ##
==========================================
- Coverage   87.65%   87.63%   -0.03%     
==========================================
  Files          23       23              
  Lines       17503    17523      +20     
  Branches     3451     3450       -1     
==========================================
+ Hits        15343    15357      +14     
- Misses       1058     1062       +4     
- Partials     1102     1104       +2     

Flag	Coverage Δ
#c_tests	88.89% <ø> (ø)
#python_c_tests	91.05% <87.50%> (-0.06%)	⬇️
#python_tests	98.95% <ø> (ø)

Impacted Files	Coverage Δ
python/_tskitmodule.c	83.83% <87.50%> (-0.07%)	⬇️

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[jeromekelleher]

LGTM. I think we could take the opportunity to refactor a little bit to reduce duplication in the metadata/schema set/get code paths.

[benjeffery]

@jeromekelleher Ready for review

(env) benj@treebeard:~/projects/tskit/python$ python stress_lowlevel.py -m lowlevel
iter	tests	err	fail	skip	RSS	min	max	max@iter
309	174	0	0	0	80320	79976	80320	1

[jeromekelleher]

LGTM - small formatting problem.

[benjeffery]

@mergify refresh

[mergify]

Command refresh: success

Hey, I reacted but my real name is @Mergifyio

[benjeffery]

travis is AWOL, attempting to kick it into gear