Text download (green arrow) on Note documents truncates content with accentuated chars

Reason:

• The Note download button uses the nxbigfile servlet on the BlobHolder
• The BlobHolder adapts the String content of the note as a StringBlob instance
• StringBlob#getLength returns size of chars instead of size in bytes

Fix:

StringBlob#getLength should return size in bytes (depends on encoding) as stated in the Blob#getLength javadoc.