support for ensembles with custom weights

[codecov[bot]]

Codecov Report

Merging #46 (d81bfff) into master (d86c04f) will increase coverage by 0.69%. The diff coverage is 98.98%.

@@            Coverage Diff             @@
##           master      #46      +/-   ##
==========================================
+ Coverage   97.65%   98.35%   +0.69%     
==========================================
  Files          14       14              
  Lines        1024     1094      +70     
==========================================
+ Hits         1000     1076      +76     
+ Misses         24       18       -6     

Files	Coverage Δ
R/crosspred.R	99.04% <100.00%> (+5.91%)	:arrow_up:
R/ddml_ate.R	98.03% <100.00%> (+0.08%)	:arrow_up:
R/ddml_att.R	97.91% <100.00%> (+0.06%)	:arrow_up:
R/ddml_fpliv.R	98.67% <100.00%> (+0.25%)	:arrow_up:
R/ddml_late.R	97.33% <100.00%> (+0.11%)	:arrow_up:
R/ddml_pliv.R	100.00% <100.00%> (ø)
R/ddml_plm.R	97.33% <100.00%> (+0.27%)	:arrow_up:
R/ensemble.R	100.00% <100.00%> (ø)
R/get_CEF.R	96.15% <100.00%> (+0.32%)	:arrow_up:
R/shortstacking.R	98.27% <85.71%> (+0.16%)	:arrow_up: