Make tox.c unambiguously parseable.

[iphydf]

Rules:

1. Constants are uppercase names: THE_CONSTANT.
2. SUE[1] types start with an uppercase letter and have at least one
   lowercase letter in it: The_Type, THE_Type.
3. Function types end in "_cb": tox_friend_connection_cb.
4. Variable and function names are all lowercase: the_function.

This makes it easier for humans reading the code to determine what an
identifier means. I'm not convinced by the enum type name change, but I
don't know a better rule. Currently, a lot of enum types are spelled like
constants, which is confusing.

[1] struct/union/enum

---

This change is 

[sudden6]

For the enum types, what do you want to express with making them different than constants? Because as far as I know when compiling they are constant then.

Reviewed 19 of 21 files at r1.
Reviewable status: 0 of 1 LGTMs obtained

---

toxcore/Messenger.h, line 139 at r1 (raw file):

    USERSTATUS_BUSY,
    USERSTATUS_INVALID
} Userstatus;

somehow my eyes expect UserStatus here, change?

[iphydf]

The enum values should be constants, but the enum types aren't constants. They are types, and should be spelled like types.

Reviewable status: 0 of 1 LGTMs obtained

---

toxcore/Messenger.h, line 139 at r1 (raw file):

Previously, sudden6 wrote…

somehow my eyes expect UserStatus here, change?

User_Status, since that's the naming standard in toxcore (I think it's ew, but oh well).

[sudden6]

ah, right, then it's fine for me

Reviewable status: complete! 1 of 1 LGTMs obtained

---

toxcore/Messenger.h, line 139 at r1 (raw file):

Previously, iphydf wrote…

User_Status, since that's the naming standard in toxcore (I think it's ew, but oh well).

ok, User_Status looks slightly better...