Firefox addon: Let XHR respect private mode
Merge pull request #4235 from Rob--W/firefox-addon-xhr-private

[privacy] Respect private browsing mode in Firefox add-on
Rewrite Lexer_getNumber.
Now, it computes the numbers with only basic arithmetic operations, without first creating a string and then calling parseFloat.
The new function doesn't behave exactly the same as the old one.
In particular, the old behaviour was that when there was a number immediatly followed by an 'E', the 'E' was consumed. Now it's not. It allows for "glued" numbers and operators.
Also, the new function is faster and consumes less memory.
Add @lovasoa to AUTHORS