Fixes for #64 and #65

[donaldcampbelljr]

Fixes #64
Adds enhancement #65

For #64, note that the start and core wiggles will be shifted by 1 since we are converting from bed files(0 based) to wiggles (1 based). The npy files are not shifted so the start and core positions will be 1 less than the wiggle counter parts.

However, because a bed file's end positions are 1 based, no shifting is done for the ends. Therefore, the npy and wig start positions for the end files should be the same.

[donaldcampbelljr]

@ClaudeHu please test this and confirm it meets your needs. See above for differences between wig and npy start positions.

[codecov]

Codecov Report

Attention: Patch coverage is 92.20779% with 6 lines in your changes missing coverage. Please review.

Project coverage is 61.22%. Comparing base (47b6316) to head (8ae3d41).
Report is 3 commits behind head on dev.

Files with missing lines	Patch %	Lines
gtars/src/uniwig/mod.rs	91.54%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev      #66      +/-   ##
==========================================
+ Coverage   61.11%   61.22%   +0.11%     
==========================================
  Files          37       37              
  Lines        6061     6094      +33     
==========================================
+ Hits         3704     3731      +27     
- Misses       2357     2363       +6     

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[ClaudeHu]

@ClaudeHu please test this and confirm it meets your needs. See above for differences between wig and npy start positions.

Now the values from different output format are consistent. Tested with with geniml.universe in progress, and the arrays read from .bw (converted by wig2bigwig) and .npy are identical. Thanks!