* The reset method expects 5 to 6 arguments:
     * - The first argument is the format string used to display the progress
     *   bar. It may (and should) contain placeholders that the class will
     *   replace with information like the progress bar itself, the progress in
     *   percent, and so on. Current placeholders are:
     *     %bar%         The progress bar
     *     %current%     The current value
     *     %max%         The maximum malue (the "target" value)
     *     %fraction%    The same as %current%/%max%
     *     %percent%     The status in percent
     *     %elapsed%     The elapsed time
     *     %estimate%    An estimate of how long the progress will take
     *   More placeholders will follow. A format string like:
     *   "* stuff.tar %fraction% KB [%bar%] %percent%"
     *   will lead to a bar looking like this:
     *   "* stuff.tar 391/900 KB [=====>---------]  43.44%"
     * - The second argument is the string that is going to fill the progress
     *   bar. In the above example, the string "=>" was used. If the string you
     *   pass is too short (like "=>" in this example), the leftmost character
     *   is used to pad it to the needed size. If the string you pass is too long,
     *   excessive characters are stripped from the left.
     * - The third argument is the string that fills the "empty" space in the
     *   progress bar. In the above example, that would be "-". If the string
     *   you pass is too short (like "-" in this example), the rightmost
     *   character is used to pad it to the needed size. If the string you pass
     *   is too short, excessive characters are stripped from the right.
     * - The fourth argument specifies the width of the display. If the options
     *   are left untouched, it will tell how many characters the display should
     *   use in total. If the "absolute_width" option is set to false, it tells
     *   how many characters the actual bar (that replaces the %bar%
     *   placeholder) should use.
     * - The fifth argument is the target number of the progress bar. For
     *   example, if you wanted to display a progress bar for a download of a
     *   file that is 115 KB big, you would pass 115 here.
     * - The sixth argument optional. If passed, it should contain an array of
     *   options. For example, passing array('absolute_width' => false) would
     *   set the absolute_width option to false. Current options are:
     *     option             | def.  |  meaning
     *     --------------------------------------------------------------------
     *     percent_precision  | 2     |  Number of decimal places to show when
     *                        |       |  displaying the percentage.
     *     fraction_precision | 0     |  Number of decimal places to show when
     *                        |       |  displaying the current or target
     *                        |       |  number.
     *     percent_pad        | ' '   |  Character to use when padding the
     *                        |       |  percentage to a fixed size. Senseful
     *                        |       |  values are ' ' and '0', but any are
     *                        |       |  possible.
     *     fraction_pad       | ' '   |  Character to use when padding max and
     *                        |       |  current number to a fixed size.
     *                        |       |  Senseful values are ' ' and '0', but
     *                        |       |  any are possible.
     *     width_absolute     | true  |  If the width passed as an argument
     *                        |       |  should mean the total size (true) or
     *                        |       |  the width of the bar alone.
     *     ansi_terminal      | false |  If this option is true, a better
     *                        |       |  (faster) method for erasing the bar is
     *                        |       |  used. CAUTION - this is known to cause
     *                        |       |  problems with some terminal emulators,
     *                        |       |  for example Eterm.
     *     ansi_clear         | false |  If the bar should be cleared everytime
     *     num_datapoints     | 5     |  How many datapoints to use to create
     *                        |       |  the estimated remaining time
     *     min_draw_interval  | 0.0   |  If the last call to update() was less
     *                        |       |  than this amount of seconds ago,
     *                        |       |  don't update.
     *