from  Benoît Perrot  <benoit@lrde.epita.fr>

	Strengthen lexical analysis.
	
	* dev/parse-asm-scan-gen.py: Complain when a lexicaly correct
	integer cannot be converted by istringstream, for example when the
	said integer is too large. For hexadecimal integers, a maximal
	number of digits might be used, but it seems more generic to
	handle it through istringstream; never knowns, someday nolimips
	may have to support 64 or event 128 bits long integers :). Call
	step() each time an invalid character is detected, to have a more
	clever error message. Step only one line when an eol sequence is
	detected.
	* tests/lexical/invalid-characters.s, integer-too-large.s: New.
	* tests/lexical/Makefile.am: Update accordingly.