Feature #43 - Relative dates: +3d, -2w

- Added feature #43, now task supports relative dates like '3wks',
  '1 month', '4d' for 'due', 'wait' and 'until' dates.  Essentially
  durations are now allowed where dates are expected, and are treated
  as relative to the current date/time.

ChangeLog

@@ -2,6 +2,10 @@
 ------ current release ---------------------------
 
 1.9.3 ()
+ + Added feature #43, now task supports relative dates like '3wks',
+   '1 month', '4d' for 'due', 'wait' and 'until' dates.  Essentially
+   durations are now allowed where dates are expected, and are treated
+   as relative to the current date/time.
  + Added feature #189, that records the start and stop times
    as an annotation for a task.
  + Added feature #391, now the 'task color legend' command will show

NEWS

@@ -3,6 +3,9 @@ New Features in task 1.9.3
 
   - Start and stop times for a task can now be recorded as annotations.
   - Special tags 'nocolor', 'nocal' and 'nonag'.
+  - Now supports durations in dates, such as:
+      $ task ... due:4d
+      $ task ... due:3wks
 
   Please refer to the ChangeLog file for full details.  There are too many to
   list here.
@@ -11,12 +14,10 @@ New commands in task 1.9.3
 
   - New 'task color legend' command will show samples of all the defined colors
     and color rules from your .taskrc and theme.
-  -
 
 New configuration options in task 1.9.3
 
   - journal.time, journal.time.start.annotation, journal.time.stop.annotation
-  -
 
 Newly deprecated features in task 1.9.3
 

doc/man/task.1

@@ -335,7 +335,7 @@ Attribute modifiers improve filters.  Supported modifiers are:
 .br
 .B  isnt       (synonym not)
 .br
-.B  has        (synonym contain)
+.B  has        (synonym contains)
 .br
 .B  hasnt
 .br
@@ -374,11 +374,17 @@ task ... due:today
 .br
 task ... due:yesterday
 .br
-task ...  due:tomorrow
+task ... due:tomorrow
 
 .TP
 Day number with ordinal
 task ... due:23rd
+.br
+task ... due:3wks
+.br
+task ... due:1day
+.br
+task ... due:9hrs
 
 .TP
 End of week (Friday), month and year