Update grammar of internals.rst

Some changes that I think help the docs read easier.

doc/internals.rst

@@ -42,7 +42,7 @@ an instance of ``Twig_Token``, and the stream is an instance of
 * ``Twig_Token::EOF_TYPE``: Ends of template.
 
 You can manually convert a source code into a token stream by calling the
-``tokenize()`` of an environment::
+``tokenize()`` method of an environment::
 
     $stream = $twig->tokenize($source, $identifier);
 
@@ -63,7 +63,7 @@ Here is the output for the ``Hello {{ name }}`` template:
 
 .. note::
 
-    You can change the default lexer use by Twig (``Twig_Lexer``) by calling
+    The default lexer (``Twig_Lexer``) can be changed by calling
     the ``setLexer()`` method::
 
         $twig->setLexer($lexer);
@@ -97,7 +97,7 @@ Here is the output for the ``Hello {{ name }}`` template:
 
 .. note::
 
-    The default parser (``Twig_TokenParser``) can be also changed by calling the
+    The default parser (``Twig_TokenParser``) can be changed by calling the
     ``setParser()`` method::
 
         $twig->setParser($parser);
@@ -108,13 +108,11 @@ The Compiler
 The last step is done by the compiler. It takes a node tree as an input and
 generates PHP code usable for runtime execution of the template.
 
-You can call the compiler by hand with the ``compile()`` method of an
-environment::
+You can manually compile a node tree to PHP code with the ``compile()`` method
+of an environment::
 
     $php = $twig->compile($nodes);
 
-The ``compile()`` method returns the PHP source code representing the node.
-
 The generated template for a ``Hello {{ name }}`` template reads as follows
 (the actual output can differ depending on the version of Twig you are
 using)::
@@ -134,7 +132,7 @@ using)::
 
 .. note::
 
-    As for the lexer and the parser, the default compiler (``Twig_Compiler``) can
-    be changed by calling the ``setCompiler()`` method::
+    The default compiler (``Twig_Compiler``) can be changed by calling the
+    ``setCompiler()`` method::
 
         $twig->setCompiler($compiler);