Update hashcat mode rules for character class support

Once https://github.com/hashcat/hashcat/pull/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).

Review the CLASS_export_pos macro shown in the issue and the related hashcat pull request 4107 before changing hashcat-mode handling. Trace how the purge command and other commands use this macro, then verify that character classes and the noted hashcat exceptions behave correctly in hashcat mode.