Convert closed_check to to_close; closed_check for valid reasons.

We had someone closed who wasn't triple negative, so I'm adding a check for
that; but `closed_check` makes way more sense, so I'm migrating its current
functionality (checking for people *to close*) to `to_close`.

I can get away with this because I have no collaborators.
Add a marker for closed parts. with missing tests.
Checking closings based on most recent tests for each participant.

Also - sometimes their test records are entirely missing. That counts, too.
Show only missing heights and weights, not unknowns. Fixes #14.

Height and weight both have metavariables with an indicator for "I Don't Know"
 - that's not missing, it's unknown.  This incorporates that metavariable into
the function and returns only the genuinely missing.
Slightly improved plot label
Data now available in zip - update import to match.

Instead of unzipping all the files, it's easier to just read them straight
out of the file.  There can still only be one data file in the extracts
directory at a time, however.
Ensure that this rename is used, not plyr's
Ensure that LocalIDs come through as character.
Fix ID -> NA conversion
Convert LTBI treatment dates to Dates.
Fix record-as-header error in import

I was accidentally reading in the first record of these files as headers -
identified only by finding a treatment record missing from one participant.
Correct age calculation in lubridate. Fixes #18.

LET ITS SYNTAX RING THROUGH THE AGES
Add a function to identify out-of-bounds follow-ups.
Clarify WTF 'VisitDate' actually means on each table.

My naming convention here is that VisitDate should always mean the date of
whatever the table is recording - so "VisitDate" on the preenrollment table
means the preenrollment date, on the followupfortb table it means the follow-up,
etc. Thus, all the places where VisitDate has been tacked on by the DMS guys
are now "EnrollDate" - since they came off of the master table.
Percolate "EnrollDate" through all the functions. Fixes #17.

One slight variation: I'm calling it EnrollDate on the master table, too,
so that its naming is consistent whether the DMS guys merged it onto a file
or I did.
Convert more Dates.  Fixes #15.
Make StudyId on master consistent with StudyID on everything else.
Now that StudyID comes on every table in the DMS export, mix is obsolete.

All it was doing was adding StudyId to each table. No longer necessary.
Closes #16.
Now that StudyID comes on every table in the DMS export, mix is obsolete.

All it was doing was adding StudyId to each table. No longer necessary.
Closes #16.
Merge branch 'master' of https://github.com/mmparker/to1check