fix the "DATES" keyword

The time of the day field was missing. The defaults for it are those
of E100.
fix the definition of the START keyword

this one had the same problems as DATES
trivial: fix end-of-file comment in Completion.hpp

that clearly was a copy-and-pasteo...
TimeMap: replace boost::gregorian::date by boost::posix_time::ptime

this is necessary because boost::gregorian::date does not have a
notion of "time during a day" which is required to specify time step
lengths less than a day...
TimeMap: simplify the initialization of the eclipse month name map slightly
TimeMap: Expose more data

basically, we now can access the beginning of a timestep its length
and the total time passed since the beginning of life, the universe
and all the rest.
TimeMap: add constructor which takes a deck

this simplifies things considerably and hopefully avoids code
excessive code duplication..
TimeMap: extend test to check "from deck construction" and the new accessor methods
fixup! TimeMap: add constructor which takes a deck
fixup! TimeMap: Expose more data
TimeMap: always assume the presence of the TIME item

i.e., the number of items in a date record must now always be 4. to
make this happen, some tests had to be fixed, too...
Merge pull request #129 from andlaus/refactor_timemap

Refactor timemap