Update hashcat mode rules for character class support

[solardiz]

Once hashcat/hashcat#4107 is merged, we'll need to enable our class support in the purge command also in hashcat mode. It is currently disabled with the check here:

#define CLASS_export_pos(start, true, false) { \
        char value, *class; \
        if (((value = RULE) == '?') && !hc_logic) { \

This may be a bit complicated because:

1. It looks like hashcat is currently only adding class support to this one command, whereas we use the same macro for many commands.
2. hashcat will likely add exceptions where @? followed by some characters found in existing rulesets is treated the same as @??. We'll likely want to mimic those exceptions when in hashcat mode (or we'll need to update our copies of hashcat style rulesets to use @?? where appropriate - it's just 3 places).

[solardiz]

The referenced hashcat pull request has changed a lot since I posted the original description of this issue. It isn't yet clear what will actually go into hashcat, and thus what changes we need to make here, but now it looks likely that hashcat will implement character classes not only for the purge command, but for most or all commands where we support character classes.