Use POST for guest token

Fixes #56

src/api/media.nim

@@ -51,9 +51,10 @@ proc getGuestToken(agent: string; force=false): Future[string] {.async.} =
   tokenUpdated = getTime()
   tokenUses = 0
 
-  let
-    headers = genHeaders({"authorization": auth}, agent, base, lang=false)
-    json = await fetchJson(apiBase / tokenUrl, headers)
+  let headers = genHeaders({"authorization": auth}, agent, base, lang=false)
+  newClient()
+
+  let json = parseJson(await client.postContent($(apiBase / tokenUrl)))
 
   if json != nil:
     result = json["guest_token"].to(string)

src/query.nim

@@ -110,6 +110,7 @@ proc cleanPos*(pos: string): string =
   pos.multiReplace((posPrefix, ""), (posSuffix, ""))
 
 proc genPos*(pos: string): string =
+  if pos.len == 0: return
   result = posPrefix & pos
   if "A==" notin result:
     result &= posSuffix