Two differences that diverge from the existing behavior:
1. Leading zeros are not allowed for integers. Negative
octal numbers such as `-066` are not meant to be treated
as positional arguments, but existing code recognize them
as decimal numbers. Note that negative floating-point
numbers with leading zeros (`-003.`) are unambiguous and
are recognized.
2. Inf and NaN are not recognized. This is because options
like `-inf` is indistinguishable from a compound argument
that meant to be a shorthand for `-i -n -f`.
fixes: p-ranav/argparse#55
This change also explicitly lists the source files
for CMake. This is because `GLOB` does not remove
old files when switching branches in Git, and
`CONFIGURE_DEPENDS` will add unstaged files after
stashing.
See also: https://cmake.org/cmake/help/latest/command/file.html#glob
