BOM breaks parseXmlDeclaration

[ppebb]

In files containing a BOM (utf <feff>) at the beginning of the file, parseXmlDeclaration in XmlParser.lua will error thinking that the XML declaration is not at the beginning of the string.

local xml2lua = require("xml2lua")
local handler = require("xmlhandler.tree")
local h = handler:new()
local parser = xml2lua.parser(h)

parser:parse("<?xml version=\"1.0\" encoding=\"utf-8\"?>")

Running this snippet (ensure you copy and paste, as there is an invisible BOM right before the <) will produce the following output:

./xml2lua.lua:92: XMLDecl not at start of document [char=1]

stack traceback:
	[C]: in function 'error'
	./xml2lua.lua:92: in field 'errorHandler'
	./XmlParser.lua:133: in upvalue 'err'
	./XmlParser.lua:194: in upvalue 'parseXmlDeclaration'
	./XmlParser.lua:347: in upvalue 'parseTagType'
	./XmlParser.lua:429: in function 'XmlParser.parse'
	stdin:6: in main chunk
	[C]: in ?```