date: accept time as a widget argument

Format custom time for example to calculate time zone differences, New
York time relative to me would be widget argument: os.time()-21600

README

@@ -265,8 +265,10 @@ vicious.widgets.weather
     {windkmh}, {sky}, {weather}, {tempf}, {tempc}, {humid}, {press}
 
 vicious.widgets.date
-  - provides access to os.date, with optional custom formatting;
-    provided as the format string
+  - provides access to os.date, with optional time formatting provided
+    as the format string
+  - takes optional time as an argument, for example to calculate
+    time-zone differences, otherwise it formats the current time
   - returns the output of os.date(), formatted by provided sequences
 
 

widgets/date.lua

@@ -10,13 +10,13 @@ local setmetatable = setmetatable
 -- }}}
 
 
--- Date: provides access to os.date with optional custom formatting
+-- Date: provides access to os.date with optional time formatting
 module("vicious.widgets.date")
 
 
 -- {{{ Date widget type
-local function worker(format)
-    return os.date(format or nil)
+local function worker(format, warg)
+    return os.date(format or nil, warg or nil)
 end
 -- }}}