Ensure that the docs examples verify as Cretonne IL.

Any *.cton files in the docs directory are now included when running the
test-all.sh script. This is to ensure that the examples are in fact
correct IL.

Always print NaN and Inf floats with a sign. Print the positive ones as
+NaN and +Inf to make them easier to parse.

cranelift/docs/cton_lexer.py

@@ -39,7 +39,7 @@ class CretonneLexer(RegexLexer):
             # Numbers.
             (r'[-+]?0[xX][0-9a-fA-F]+', Number.Hex),
             (r'[-+]?0[xX][0-9a-fA-F]*\.[0-9a-fA-F]*([pP]\d+)?', Number.Hex),
-            (r'[-+]?(\d+\.\d+([eE]\d+)?|[sq]NaN|Inf)', Number.Float),
+            (r'[-+]?(\d+\.\d+([eE]\d+)?|s?NaN|Inf)', Number.Float),
             (r'[-+]?\d+', Number.Integer),
             # Known attributes.
             (keywords('align', 'aligntrap', 'uext', 'sext', 'inreg'),