Actigraph date format with hyphens now recognized

Minor fix to ensure that Actigraph date formats with hyphen separators can be recognized, see issue #18

dynrange and g.inspectfile fix

• Argument dynrange added as a way to overwrite the hardcoded assumed dynamic range per accelerometer brand (8 g for Axivity and GENEAcitv, 6 g for GENEA and Actigraph). This will help to better identify signal clipping
• Function g.inspectfile was not able to handle .cwa format data, now fixed

cwa functionality routine registration bug fix

See #6, hopefully this is now fixed

g.cwaread functionality reimplemented

Following issue #6, I reimplemented the cpp code in the package

bugs fixed cwa-format + vignette added

• Vignette added
• Bugs fixes in relation to new cwa-read functionality
• Bugs fixes in correct number of days recognition in part5

cwa-format and IS IV metrics

• Removed teLindert2013 metric, because it was not used and not verified
• Split g.getmeta function into multiple smaller functions
• Added IS and IV variables to g.analyse (still in explorative version)
• bug fixed related to wav file read errors
• function g.cwaread added (credits to E. Mirkes) for reading Axivity .cwa-format data. g.shellGGIR will automatically use this function when input data has .cwa extension
• bug fixed related to for GENEactiv starttime recognition which was introduced in version 1.2-11
• g.part5 documentation added on its output