Observations snapping and tests

[jGaboardi]

This PR adds a new class: Observations with snapping functionality and tests.

[codecov]

Codecov Report

Merging #38 (6a0c5d6) into main (40db3bb) will increase coverage by 1.1%.
The diff coverage is 92.4%.

@@           Coverage Diff           @@
##            main     #38     +/-   ##
=======================================
+ Coverage   82.7%   83.8%   +1.1%     
=======================================
  Files          5       5             
  Lines       1074    1193    +119     
  Branches     277     301     +24     
=======================================
+ Hits         888    1000    +112     
- Misses       120     124      +4     
- Partials      66      69      +3     

Impacted Files	Coverage Δ
tigernet/tigernet.py	91.7% <89.7%> (-0.4%)	⬇️
tigernet/utils.py	78.8% <93.8%> (+1.9%)	⬆️