Attribute value supports rml escape

[actboy168]

This change allows escaping of element attributes. e.g.

<div data-style-decorator="'image(&quot;image.png&quot;)'" />

[mikke89]

Thanks!

Some issues though:

• The text comparisons are potentially out-of-bound accesses. They need to be guarded by the string size.
• We can avoid an allocation by taking the input string by-value instead of const reference, and moving in the value parameter in BaseXmlParser. Then do the search and replace within the input string and return.

Also, I don't think we actually support quotes in the string property parser, it just consumes the whole thing. So you don't actually need the " there as in your example. Which leads to the question if we really need this change?

[actboy168]

1. I think it will not be out-of-bound. Because the string always contains'\0' as the end, it will exit when it finds'\0'.
2. I just want to be consistent with the function definition of EncodeRml. If it needs optimization, I can modify it.
3. How do you think that my example should be implemented without "?

[mikke89]

1. I had to double check with the specs, and it looks like you're right.
2. Makes sense, I'll go over them both at some point.
3. It should just be:

<div data-style-decorator="'image(image.png)'" />

I'll merge this, as there could be other use cases, and I consider this a more correct approach. Plus, I couldn't measure any performance degradation. So that's good :) Thanks!