Add generic type support

[sunsided]

This makes the filter and matrix types generic on T, which defaults to f32. This should be the first step in supporting arbitrary precision and fixed-point calculation.

[codecov]

Codecov Report

Attention: Patch coverage is 85.21401% with 38 lines in your changes missing coverage. Please review.

Project coverage is 87.20%. Comparing base (0dfef1a) to head (87a6299).
Report is 1 commits behind head on main.

Files	Patch %	Lines
src/kalman.rs	69.89%	28 Missing ⚠️
src/matrix.rs	93.06%	7 Missing ⚠️
src/measurement.rs	95.23%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #5      +/-   ##
==========================================
+ Coverage   86.96%   87.20%   +0.23%     
==========================================
  Files           4        4              
  Lines        1343     1391      +48     
==========================================
+ Hits         1168     1213      +45     
- Misses        175      178       +3     

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