Sync src with amalgamated versions

Now src contains exactly what's embedded in mongoose.c and .h, nothing more.

Added `tools/amalgam.sh` to aamlgamate both files at once.

There are no functional changes to mongoose.c, .h in this PR, only slight filename changes.

src/mg_http.c

@@ -1,7 +1,3 @@
-/*
- * Copyright (c) 2014 Cesanta Software Limited
- * All rights reserved
- */
 
 #if MG_ENABLE_HTTP