The custom implementations of 'strtof' and 'strndup'
present in the svg loader have been moved into a new
'utils' directory (strToFloat and strDuplicate, respectively).
The custom _strndup was used only in one file
as an internal function and wasn't accessible
in other parts of the code. Now function
is available as svgUtilStrndup.
This patch introduces embeded <image> tag for svg files.
Images can be now loaded from local path or using data URI Scheme (RFC2397).
Base64 and utf8/uri are welcome.
@issue: #518
