[R-pkgs] Major update: icd9 1.0

[Jack Wasey]

Dear R users,

An updated icd9 package is now on CRAN.

Calculate comorbidities, and perform fast and accurate validation,
conversion, manipulation, filtering and comparison of ICD-9-CM
(clinical modification) codes. The package enables a work flow from
raw lists of ICD-9 codes from hospital billing databases to
comorbidities. ICD-9 to comorbidity mappings from Quan (Deyo and
Elixhauser versions), Elixhauser and AHRQ included.

A vignette describes the main features:
http://cran.r-project.org/web/packages/icd9/vignettes/introduction.html

# Version 1.0

* Calculate Charlson scores
* Sum distinct comorbidities or diagnoses by patient
* Core rewrite in C++ for 50+ times speed improvement. 100,000
patients assigned comorbidities in ~2 seconds.
* Simplified handling validation of codes. No longer done in every function.
* Most functions now guess the ICD-9 code type automatically (e.g.
00321 vs 003.21)
* Reduced external dependencies down to Rcpp and checkmate (a very
lightweight and fast function argument checker)
* Bug fixes (see
[github](https://github.com/jackwasey/icd9/issues?q=is%3Aissue+is%3Aclosed))
* API changes
    - no more validation except in the icd9IsValidXxx functions.
Removed stopIfInvalidIcd9, icd9InvalidActions
    - internalized utility functions. They are also packaged and
tested in [jwutil](http://cran.r-project.org/web/packages/jwutil/index.html)
    - deprecated icd9ValidXxx in favour of icd9IsValidXxx
    - deprecated icd9ComorbditiesXxx replacing with briefer icd9ComorbidXxx
    - stopped exporting benchmarking and SAS code processing.

Comments and contributions very welcome via github:
https://github.com/jackwasey/icd9

Jack Wasey