more numeric tag tests needed

[rogpeppe]

Possible additional tests:

Numbers with different bases (0x, 0b, 0o)
Numbers which might be interpreted wrongly (e.g. 0755)
Numbers with inappropriate tags (e.g. `!!float 0xff`)

[rogpeppe]

Another test:

! 9

(expected json is "9" but several YAML parsers don't interpret the ! correctly and produce 9 instead)

[perlpunk]

You can find such tests here: https://github.com/perlpunk/yaml-test-schema