Add non-functional lib/csvfile.php.
(cherry picked from commit 34b4960d5659fdff1d0043c09aa193f10f3e5b50)

CsvFile will now parse a csv file and return an object with errors, headers, and data.
(cherry picked from commit ac62b4a53265ded746e32dfb2f41943bf62c849a)

Use mandatory fields correctly in csvfile.php.
(cherry picked from commit e378fc7de6f127cd0c9bc3ab48912466f3d42351)

Remove checking for an error that will never be reached.
(cherry picked from commit 36f2a90218145f349763aada2c469fd5e6eade71)

Replace references to headers with format.
(cherry picked from commit 002a602cc016986df03752bca551832bbb3ffda9)

Throw exception for no CSV header row if there are no other errors.
(cherry picked from commit e09686075502c50506ebd0dc737021914d1ec03c)

Update uploadcsv.php to use csvfile.php
(cherry picked from commit 4070d03a0c7ff811361038781bd3194d5b98d4b0)

Set an error on the upload users form and return if a duplicate email address is found.
(cherry picked from commit f6dba540e90582b139d0748802f40e3cc1865c49)

Also check profile for duplicate email addresses.
(cherry picked from commit 4f5d8eb661c8abd8d9553e3c193d7f15397a91ee)

Add checks to see if the filename exists.
(cherry picked from commit ba5bdb0e9c9dbc77a422d48c3a0609258a2b0c15)

Add a TODO for documenting csvfile.php.
(cherry picked from commit a3ebd09be81f8908aa2cdd35a92798ea937cffc6)