Added a couple of experimental functions

[aasiyahrashan]

Functions which test methods of incorporating the apache ii score into
this package.
Function gen_neuro calculates gcs component of either SOFA or APACHE II score.
gen_apache_hr calculates the heart rate component of apache ii only.

Documentation has only been partially edited.

[codecov-io]

Codecov Report

Merging #7 into master will decrease coverage by 0.37%.
The diff coverage is 36.66%.

@@            Coverage Diff             @@
##           master       #7      +/-   ##
==========================================
- Coverage   41.75%   41.37%   -0.38%     
==========================================
  Files          17       19       +2     
  Lines         376      406      +30     
==========================================
+ Hits          157      168      +11     
- Misses        219      238      +19

Impacted Files	Coverage Δ
R/gen_apache_hr.R	0% <0%> (ø)
R/gen_neuro.R	57.89% <57.89%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 58e43ab...88adcf3. Read the comment docs.