vast improvement in dealing with Present-on-Arrival flags
* replace icd9ComorbidPoa functions with icd9FilterPoaYes etc., which allow chaining with magrittr
* improve documentation about Quan/Deyo cancers all grouped together
* drop sysdata for two public vectors so they are user (and vignette) accessible.
* vignette updates to show off filtering

* ignore compiled objects
test POA filtering
* tests for majority of cases
* bring defactor of icd9 codes outside of vapply loop in icd9Comorbidities
* tolerate upper and lower case POA
* vignette block names and minor updates
Co-morbidity handling much improved.
 * Bump version in anticipation of a release.
 * Specific functions for applying mappings to lists of icd9 codes, one for each co-morbidity, each performing mapping-specific details like not double counting mild and severe liver disease. Will someday be relatively easier to convert this to inherited classes but at present this is not worth the clumsiness of doing it in R S4/5 objects.
 * pre-set naming scheme: considerable overlap for the Elixhauser-based mappings. Have provided full and short names for each co-morbiditity. Several permutations because of HTN handling.
 * resaved data files and updated tests using the standardized the naming scheme
 * tweaked documentation in R/convert.R
tests for sample of content of mappings
fix test to accurately reflect that HTN in pregnancy should be categorized as HTN with complications in AHRQ mapping.
Tests for new functions for application of comorbidities, other fixes
* typos in datadocs
* vignette compiles now
progress towards passing tests for new functions for assigning comorbidities
Passes all new tests for new comorbidity extraction functions
 * new tests in test-comorbid.R covering all combinations of naming and restructuring when generating comorbidities
 * comorbid.R updated accordingly
Close to 0.4 release: mostly docs and vignette updates.
Summary of changes:
* Present-on-arrival field handled gracefully
* Revised co-morbidity handling, with functions specific to each mapping
* Standardized naming of fields across Elixhauser and Charlson based mappings for clarity, consistency and comparaibility
* Handle mild and severe co-morbidities without double-counting. Fixes issue #23
* Enable magrittr-style piping as option to clarify chains of operations. Issue #5
* many more test cases, including specific tests for individual values in each computed mapping, and also for the new comorbidity functions
* Vignette updated to demonstrate clearer new functions
tidied up documentation to pass R CMD check. Primarily docs for mapping name data.
Tidied up for CRAN
* tweaked docs for output width
* don't run a slow example (similar code appears in vignette)
* passes check as CRAN
resolve minor merge conflict

Merge branch 'master' of github.com:jackwasey/icd9

Conflicts:
	R/comorbid.R
	vignettes/icd9.Rnw