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Fix some errors in README

There a few problems in README about volatile and const. They are fixed
now although we should change the text to show that we want to implement
volatile in the future.

--- a/README

+++ b/README

@@ -10,8 +10,8 @@

 Type qualifers make the type system ugly, and their uselessness add

 unnecessary complexity to the compiler (and increased compilation time):

 	- const: The definition of const is not clear in the standard.

-	  If a const value is modified the behaviour is implementation

-	  defined. It seems it was defined in order to be able to

+	  If a const value is modified the behaviour is undefined

+	  behaviour. It seems it was defined in order to be able to

 	  allocate variables in ROM rather than error detection. This

 	  implememtation will not warn about these modifications and

 	  the compiler will treat them like normal variables (the standard

@@ -22,13 +22,13 @@

 	  volatile have undefined state) and for memory mapped registers

 	  or variables whose values are modified asynchronously. This can

 	  be achieved with special pragma values though.

-	  In the first case, this is non-portable code by definition

+	  In the first case, it generates a lot of problems with modern

+	  processors and multithreading, where not holding the value in a

+	  register is not good enough (an explicit memory barrier is needed).

+	  In the second case, this is non-portable code by definition

 	  (depending on the register mapped), so it is better to deal with

 	  it using another solution (compiler extensions or direct

 	  assembler).

-	  In the second case, it generates a lot of problems with modern

-	  processors and multithreading, where not holding the value in a

-	  register is not good enough (an explicit memory barrier is needed).

 	- restrict: This qualifer can only be applied to pointers to

 	  mark that the pointed object has no other alias. This qualifer