Make major improvements to stdio

Buffering now has optimal performance, bugs have been fixed, and some
missing apis have been introduced. This implementation is also now more
production worthy since it's less brittle now in terms of system errors.
That's going to help redbean since lua i/o is all based on stdio.

See #97

net/http/http.h

@@ -70,7 +70,12 @@
 #define kHttpWarning            46
 #define kHttpWwwAuthenticate    47
 #define kHttpLastModified       48
-#define kHttpHeadersMax         49
+#define kHttpCookie             49
+#define kHttpTrailer            50
+#define kHttpTe                 51
+#define kHttpDnt                52
+#define kHttpExpect             53
+#define kHttpHeadersMax         54
 
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_