Lua functionality change: print renamed to mg.write, read renamed to mg.read. Expanded user manual, fixed example pages.

UserManual.md

@@ -302,35 +302,40 @@ print current weekday name, one can write:
 
     <p>
       <span>Today is:</span>
-      <? print(os.date("%A")) ?>
+      <? mg.write(os.date("%A")) ?>
     </p>
 
-Note that this example uses function `print()`, which prints data to the
-web page. Using function `print()` is the way to generate web content from
-inside Lua code. In addition to `print()`, all standard library functions
+Note that this example uses function `mg.write()`, which prints data to the
+web page. Using function `mg.write()` is the way to generate web content from
+inside Lua code. In addition to `mg.write()`, all standard library functions
 are accessible from the Lua code (please check reference manual for details),
-and also information about the request is available in `request_info` object,
+and also information about the request is available in `mg.request_info` object,
 like request method, all headers, etcetera. Please refer to
 `struct mg_request_info` definition in
 [mongoose.h](https://github.com/valenok/mongoose/blob/master/mongoose.h)
-to see what kind of information is present in `request_info` object. Also,
+to see what kind of information is present in `mg.request_info` object. Also,
 [page.lp](https://github.com/valenok/mongoose/blob/master/test/page.lp) and
 [prime_numbers.lp](https://github.com/valenok/mongoose/blob/master/examples/lua/prime_numbers.lp)
 contains some example code that uses `request_info` and other functions(form submitting for example).
 
+Mongoose exports the following to the Lua server page:
 
-One substantial difference of mongoose's Lua Pages and PHP is that Mongoose
-expects Lua page to output HTTP headers. Therefore, **at the very beginning of
-every Lua Page must be a Lua block that outputs HTTP headers**, like this:
+    mg.read()         -- reads a chunk from POST data, returns it as a string
+    mg.write(str)     -- writes string to the client
+    mg.include(path)  -- sources another Lua file
+    mg.redirect(uri)  -- internal redirect to a given URI
+    mg.onerror(msg)   -- error handler, can be overridden
+    mg.version        -- a string that holds Mongoose version
+    mg.request_info   -- a table with request information
+
+
+**IMPORTANT: Mongoose does not send HTTP headers for Lua pages. Therefore,
+every Lua Page must begin with HTTP reply line and headers**, like this:
 
     <? print('HTTP/1.0 200 OK\r\nContent-Type: text/html\r\n\r\n') ?>
     <html><body>
       ... the rest of the web page ...
 
-It is easy to do things like redirects, for example:
-
-    <? print('HTTP/1.0 302 Found\r\nLocation: http://google.com\r\n\r\n') ?>
-
 To serve Lua Page, mongoose creates Lua context. That context is used for
 all Lua blocks within the page. That means, all Lua blocks on the same page
 share the same context. If one block defines a variable, for example, that