add DSHOWHIDDENFILES in defaults.lua

this should fix #239

defaults.lua

@@ -34,6 +34,10 @@ DCREREADER_VIEW_MODE = "page"
 -- default to false
 DSHOWOVERLAP = false
 
+-- show hidden files in filemanager
+-- default to false
+DSHOWHIDDENFILES = false
+
 -- koptreader config defaults
 DKOPTREADER_CONFIG_FONT_SIZE = 1.0		-- range from 0.1 to 3.0
 DKOPTREADER_CONFIG_TEXT_WRAP = 0		-- 1 = on, 0 = off

frontend/ui/widget/filechooser.lua

@@ -6,7 +6,7 @@ FileChooser = Menu:extend{
 	no_title = true,
 	path = lfs.currentdir(),
 	parent = nil,
-	show_hidden = false,
+	show_hidden = DSHOWHIDDENFILES,
 	filter = function(filename) return true end,
 }