Return a current ti of the desired frequency
currentWeek(xTi = today())
currentMonth(xTi = today())
currentQuarter(xTi = today())
currentHalf(xTi = today())
currentYear(xTi = today())
currentQ4(xTi = today())
currentQMonth(xTi = today())
currentJanuary(xTi = today())
currentFebruary(xTi = today())
currentMarch(xTi = today())
currentApril(xTi = today())
currentMay(xTi = today())
currentJune(xTi = today())
currentJuly(xTi = today())
currentAugust(xTi = today())
currentSeptember(xTi = today())
currentOctober(xTi = today())
currentNovember(xTi = today())
currentDecember(xTi = today())a ti object or something that the ti()
  function can turn into a ti object
All return return ti objects as described in the details.
currentWeek returns the weekly ti for the week that its
  argument falls into.  If the argument is itself a ti, the
  returned week contains the last day of the argument's period. The default
  weekly frequency is "wmonday" (Monday-ending weeks), so
  currentWeek always returns wmonday ti's.  This can be
  changed via the setDefaultFrequencies function.
All of the other current{SomeFreq} functions work the same way,
  returning the ti's of tif SomeFreq that the last day of
  their arguments period falls into.  The tif's for
  currentHalf and currentQ4 are "semiannual" and
  "quarterly", respectively.  Finally, currentQMonth returns the
  quarter-ending month of the currentQuarter of its argument.
currentJanuary returns the monthly ti for January of the
  January-ending year that the last day of its argument falls into.
  currentFebruary returns the monthly ti for February of
  the February-ending year that the last day of its argument falls into,
  and so on.