add tolerance args for (l)bfgs

[jgabry]

Submission Checklist

• Run unit tests
• Declare copyright holder and agree to license (see below)

Summary

Fixes #388. Adds the remaining (l)bfgs arguments to the optimize method.

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):
Columbia University

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)

[codecov-io]

Codecov Report

Merging #398 (1e0cb7f) into master (5a02481) will increase coverage by 0.10%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #398      +/-   ##
==========================================
+ Coverage   88.37%   88.48%   +0.10%     
==========================================
  Files          12       12              
  Lines        2726     2752      +26     
==========================================
+ Hits         2409     2435      +26     
  Misses        317      317              

Impacted Files	Coverage Δ
R/args.R	99.56% <100.00%> (+0.01%)	⬆️
R/model.R	80.90% <100.00%> (+0.27%)	⬆️

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[rok-cesnovar]

Looks good to me. Thanks!

[jgabry]

Thanks. Actually I just realized that history_size only works with LBFGS and not BFGS. Will add a check for that and then merge.