altoslib: Expose locale and non-locale floating point parsing functions

altoslib: Expose locale and non-locale floating point parsing functions

UI bits use locale-specific floating point formats, so parsing those
needs to use the locale. Network-based data, like .kml bits need to
use non-locale-specific parsing code, so now we've got both APIs
available, and each used as appropriate.

Signed-off-by: Keith Packard <keithp@keithp.com>