DPIfy all themes (mostly zenburn)

This makes sure that all sizes that are specified in themes go through
the dpi() function. For most themes this just means that the value 0 is
DPIfied, which should not make much of a difference. However, for
zenburn this actually adds the very first calls to dpi() to this theme.

Fixes: https://github.com/awesomeWM/awesome/issues/1807
Signed-off-by: Uli Schlachter <psychon@znc.in>

themes/default/theme.lua

@@ -24,7 +24,7 @@ theme.fg_focus      = "#ffffff"
 theme.fg_urgent     = "#ffffff"
 theme.fg_minimize   = "#ffffff"
 
-theme.useless_gap   = 0
+theme.useless_gap   = dpi(0)
 theme.border_width  = dpi(1)
 theme.border_normal = "#000000"
 theme.border_focus  = "#535d6c"

themes/sky/theme.lua

@@ -25,7 +25,7 @@ theme.fg_focus      = "#2e3436"
 theme.fg_urgent     = "#2e3436"
 theme.fg_minimize   = "#2e3436"
 
-theme.useless_gap   = 0
+theme.useless_gap   = dpi(0)
 theme.border_width  = dpi(2)
 theme.border_normal = "#dae3e0"
 theme.border_focus  = "#729fcf"

themes/zenburn/theme.lua

@@ -4,6 +4,7 @@
 -------------------------------
 
 local themes_path = require("gears.filesystem").get_themes_dir()
+local dpi = require("beautiful.xresources").apply_dpi
 
 -- {{{ Main
 local theme = {}
@@ -24,8 +25,8 @@ theme.bg_systray = theme.bg_normal
 -- }}}
 
 -- {{{ Borders
-theme.useless_gap   = 0
-theme.border_width  = 2
+theme.useless_gap   = dpi(0)
+theme.border_width  = dpi(2)
 theme.border_normal = "#3F3F3F"
 theme.border_focus  = "#6F6F6F"
 theme.border_marked = "#CC9393"
@@ -66,8 +67,8 @@ theme.mouse_finder_color = "#CC9393"
 -- Variables set for theming the menu:
 -- menu_[bg|fg]_[normal|focus]
 -- menu_[border_color|border_width]
-theme.menu_height = 15
-theme.menu_width  = 100
+theme.menu_height = dpi(15)
+theme.menu_width  = dpi(100)
 -- }}}
 
 -- {{{ Icons