Fix various spelling mistakes (mostly in luasocket)

Thanks to Alexandre Detiste for reporting them

src/libraries/luasocket/libluasocket/http.lua

@@ -40,7 +40,7 @@ local function receiveheaders(sock, headers)
     while line ~= "" do
         -- get field-name and value
         name, value = socket.skip(2, string.find(line, "^(.-):%s*(.*)"))
-        if not (name and value) then return nil, "malformed reponse headers" end
+        if not (name and value) then return nil, "malformed response headers" end
         name = string.lower(name)
         -- get next line (value might be folded)
         line, err  = sock:receive()
@@ -67,7 +67,7 @@ socket.sourcet["http-chunked"] = function(sock, headers)
         dirty = function() return sock:dirty() end
     }, {
         __call = function()
-            -- get chunk size, skip extention
+            -- get chunk size, skip extension
             local line, err = sock:receive()
             if err then return nil, err end
             local size = base.tonumber(string.gsub(line, ";.*", ""), 16)
@@ -241,7 +241,7 @@ local function adjustrequest(reqt)
     if nreqt.port == "" then nreqt.port = 80 end
     socket.try(nreqt.host and nreqt.host ~= "", 
         "invalid host '" .. base.tostring(nreqt.host) .. "'")
-    -- compute uri if user hasn't overriden
+    -- compute uri if user hasn't overridden
     nreqt.uri = reqt.uri or adjusturi(nreqt)
     -- ajust host and port if there is a proxy
     nreqt.host, nreqt.port = adjustproxy(nreqt)

src/libraries/luasocket/libluasocket/smtp.lua

@@ -222,7 +222,7 @@ local function adjust_headers(mesgt)
     lower["date"] = lower["date"] or
         os.date("!%a, %d %b %Y %H:%M:%S ") .. (mesgt.zone or ZONE)
     lower["x-mailer"] = lower["x-mailer"] or socket._VERSION
-    -- this can't be overriden
+    -- this can't be overridden
     lower["mime-version"] = "1.0"
     return lower
 end

src/libraries/luasocket/libluasocket/url.lua

@@ -47,7 +47,7 @@ local function make_set(t)
 	return s
 end
 
--- these are allowed withing a path segment, along with alphanum
+-- these are allowed within a path segment, along with alphanum
 -- other characters must be escaped
 local segment_set = make_set {
     "-", "_", ".", "!", "~", "*", "'", "(",