use --utf8-input and --utf8-out params when calling sdcv

This will prevent string encoding conversion in Kobo in which it
has problem to doing so.
This patch should fix #252 and #272.

frontend/ui/reader/readerdictionary.lua

@@ -19,7 +19,7 @@ function ReaderDictionary:stardictLookup(word)
 		word = string.gsub(word, "%p+$", '')
 		DEBUG("stripped word:", word)
 		-- escape quotes and other funny characters in word
-		local std_out = io.popen("./sdcv -nj "..("%q"):format(word), "r")
+		local std_out = io.popen("./sdcv --utf8-input --utf8-output -nj "..("%q"):format(word), "r")
 		local results_str = std_out:read("*all")
 		if results_str then
 			--DEBUG("result str:", word, results_str)