Parse A (List Of) Tasks
parse_task.RdThis function parses one task, or a "list" (read, a vector of task
strings) in its entirety. A task is specified following the definition(s)
by Gina Trapani via todotxt.org and comprising a creation date as first
item on a line, a due date marked using due:, and a priority at the start
of each line as (X). Tags are indicated using either an @ for
(typically) contexts and a plus + for projects. Optional components
comprise a recurrence specified
using rec: as extension of the original todo.txt specification (see
documentation of the android app SimpleTask).