Create static directories at build, not runtime.

Instead of calling lfs.mkdir() to create "./history" and "./screenshots"
at runtime it is easier to create them at package build time.
I hesitated whether to add "./clipboard" to this list but decided
against it as we can perhaps change current directory and then
all the code manipulating clipboard would break, so I left it as is.

Makefile

@@ -216,7 +216,7 @@ customupdate: all
 	$(STRIP) --strip-unneeded kpdfview
 	-rm kindlepdfviewer-$(VERSION).zip
 	rm -Rf $(INSTALL_DIR)
-	mkdir $(INSTALL_DIR)
+	mkdir -p $(INSTALL_DIR)/{history,screenshots}
 	echo $(VERSION) > $(INSTALL_DIR)/git-rev
 	cp -p README.md COPYING kpdfview $(LUA_FILES) $(INSTALL_DIR)
 	mkdir $(INSTALL_DIR)/data

filechooser.lua

@@ -450,7 +450,6 @@ function FileChooser:addAllCommands()
 	self.commands:add(KEY_L, nil, "L",
 		"show last documents",
 		function(self)
-			lfs.mkdir("./history/")
 			FileHistory:init()
 			FileHistory:choose("")
 			self.pagedirty = true

screen.lua

@@ -109,7 +109,6 @@ end
 
 
 function Screen:screenshot()
-	lfs.mkdir("./screenshots")
 	local start = os.clock()
 	--showInfoMsgWithDelay("making screenshot... ", 1000, 1)
 	self:fb2bmp("/dev/fb0", lfs.currentdir().."/screenshots/"..os.date("%Y%m%d%H%M%S")..".bmp", true, nil)

settings.lua

@@ -30,7 +30,6 @@ end
 
 function DocSettings:open(docfile)
 	-- history feature moves configuration files into history directory
-	lfs.mkdir("./history")
 	local new = { file = DocToHistory(docfile), data = {} }
 	local ok, stored = pcall(dofile,new.file)
 	if not ok then