Refactor mapflags code

[Emistry]

Pull Request Prelude

• I have followed proper Hercules code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

• refactor mapflag related codes
• rearranged the codes based on mapflag index (easier for future to find and refer?)
• added missing mapflags.

	mf_nomapchannelautojoin:    61
	mf_noknockback:             62
	mf_cvc:                     63
	mf_src4instance             64

Issues addressed:
none

[4144]

While you changed map flags, probably better remove map flags duplication.
Now at same time flags added into constants.conf and in C code.
Better remove them from constants.conf and add C enum values into script engine by script->set_constant, this can reduce future errors.

[Emistry]

hmm should I keep the constants MF_*** lowercase like the old time? or uppercase is more prefer?

[Kenpachi2k13]

I'd prefer upper case for the sake of consistency.

[Kenpachi2k13]

Yeah, my fault. It's flag_name[i] != '\0'.

[MishimaHaruna]

Resolved a few remaining loose ends and force pushed