Fix wrong escaping of U+10000 to U+10FFFF range
Fix wrong escaping of U+10000 to U+10FFFF range

when serializing RubyXL::Text nodes.

mezza/rubyXL,weshatheleopard/rubyXL,mezza/rubyXL,weshatheleopard/rubyXL,weshatheleopard/rubyXL,mezza/rubyXL