Remove ModelFrame, add weights, Repeated effect vector first step

[PharmCat]

• Multiple repeated effects #34 Done
• Add weights #44 - Done
• Remove ModelFrame from model object #43 - Done

[codecov]

Codecov Report

Attention: 19 lines in your changes are missing coverage. Please review.

Comparison is base (3f3b993) 87.62% compared to head (66cd0aa) 93.19%.

Files	Patch %	Lines
src/miboot.jl	63.63%	8 Missing ⚠️
src/reml.jl	66.66%	4 Missing ⚠️
src/varstruct.jl	93.75%	3 Missing ⚠️
src/lmm.jl	95.00%	2 Missing ⚠️
src/linearalgebra.jl	90.00%	1 Missing ⚠️
src/rmat.jl	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #35      +/-   ##
==========================================
+ Coverage   87.62%   93.19%   +5.56%     
==========================================
  Files          25       24       -1     
  Lines        2861     2778      -83     
==========================================
+ Hits         2507     2589      +82     
+ Misses        354      189     -165     

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