Bug 24068: Fix I18 plugin - tnpx must call __npx

Bug 24068: Fix I18 plugin - tnpx must call __npx

Test plan:
Use the following code to test this change
    [% PROCESS 'i18n.inc' %]
    [% SET nb_stuffs = 1 %]
    [% tnpx('context', 'There is one stuff.', 'There are {count} stuffs.', nb_stuffs, { count = nb_stuffs }) | $raw  %]
    [% SET nb_stuffs = 42 %]
    [% tnpx('context', 'There is one stuff.', 'There are {count} stuffs.', nb_stuffs, { count = nb_stuffs }) | $raw  %]

Compare with and without the patch

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>