Checks that some text is multiline palindrome. Checking performs case-insensitive
		
		:param str sometext:
		    It is some string that will be checked for palindrome as multiline palindrome.
			
		    The multiline palindrome is text that contains palindrome at each line 
		    (what is the text see at help(palindromus.istext)).
			
		    Only multiline text can be the multiline palindrome.
			
		:keyword dict interchange:
		    It is dictionary of interchangeable letters
			
		:except TypeError:
		    If the checked text is not a string
			
		:return bool:

def checkmultiline(sometext, interchange = ALL):
	"""
		Checks that some text is multiline palindrome. Checking performs case-insensitive
		
		:param str sometext:
		    It is some string that will be checked for palindrome as multiline palindrome.
			
		    The multiline palindrome is text that contains palindrome at each line 
		    (what is the text see at help(palindromus.istext)).
			
		    Only multiline text can be the multiline palindrome.
			
		:keyword dict interchange:
		    It is dictionary of interchangeable letters
			
		:except TypeError:
		    If the checked text is not a string
			
		:return bool:
	"""
	# check invalid data types
	OnlyStringsCanBeChecked(sometext)
	
	if istext(sometext):
		lines = re.split(r'\r\n|\n|\r', sometext)
		if len(lines) > 1:
			for line in lines:
				if line.strip() == "":
					continue # skip empty lines
				if not checkstring(line, interchange = interchange):
					return False
			return True
	# in other cases
	return False