version 1.2.0, 2018-03-21
- conv_unit():	added "cmH2O" and "inH2O" as pressure unit options
- conv_unit():	added "km_per_hr" and "mi_per_hr" as synonyms for "kph" and "mph", respectively
- conv_unit():	fixed an issue where NAs in coordinates caused incorrect conversions

-------------------------------------------------
version 1.1.0, 2016-10-28
- conv_multiunit(): new function

-------------------------------------------------
version 1.0.0, 2016-07-26
- conv_dim():	new function
- conv_unit():	new function