[bat_openbsd] Fix compatibility with Lua 5.3 and remaining time display (#78)

Also remove duplicated environment

widgets/bat_openbsd.lua

@@ -3,14 +3,9 @@ local setmetatable = setmetatable
 local tonumber = tonumber
 local string = { format = string.format, gmatch = string.gmatch }
 local io = { popen = io.popen }
-local math = { floor = math.floor }
-local helpers = require("vicious.helpers")
-local string = {
-    gmatch = string.gmatch,
-    match = string.match,
-    format = string.format
-}
+local math = { floor = math.floor, modf = math.modf }
 -- }}}
+
 local bat_openbsd = {}
 
 local function worker(format, warg)
@@ -44,8 +39,8 @@ local function worker(format, warg)
         time = "∞"
     else
         local raw_time = bat_info.watthour3 / bat_info.power0
-	local hours = math.floor(raw_time)
-	local minutes = raw_time % 1
+        local hours, hour_fraction = math.modf(raw_time)
+        local minutes = math.floor(60 * hour_fraction)
         time = string.format("%d:%0.2d", hours, minutes)
     end