tree: Fix various typos and outdated terminology

This was mostly machine generated with the following command:
```
codespell \
    --builtin clear,rare,usage \
    --skip './po/*' --skip './.git/*' --skip './NEWS*' \
    --write-changes .
```
using the latest git version of `codespell` as per [these
instructions](https://github.com/codespell-project/codespell#user-content-updating).

Then I manually checked each change using `git add -p`, made a few
manual fixups and dropped a load of incorrect changes.

There are still some outdated or loaded terms used in GLib, mostly to do
with git branch terminology. They will need to be changed later as part
of a wider migration of git terminology.

If I’ve missed anything, please file an issue!

Signed-off-by: Philip Withnall <withnall@endlessm.com>

gio/gthreadedresolver.c

@@ -398,7 +398,7 @@ typedef struct {
 			/* fields in third byte */
 	unsigned	qr: 1;		/* response flag */
 	unsigned	opcode: 4;	/* purpose of message */
-	unsigned	aa: 1;		/* authoritive answer */
+	unsigned	aa: 1;		/* authoritative answer */
 	unsigned	tc: 1;		/* truncated message */
 	unsigned	rd: 1;		/* recursion desired */
 			/* fields in fourth byte */
@@ -412,7 +412,7 @@ typedef struct {
 			/* fields in third byte */
 	unsigned	rd :1;		/* recursion desired */
 	unsigned	tc :1;		/* truncated message */
-	unsigned	aa :1;		/* authoritive answer */
+	unsigned	aa :1;		/* authoritative answer */
 	unsigned	opcode :4;	/* purpose of message */
 	unsigned	qr :1;		/* response flag */
 			/* fields in fourth byte */
@@ -508,7 +508,7 @@ typedef enum __ns_type {
 	ns_t_cert = 37,		/* Certification record */
 	ns_t_a6 = 38,		/* IPv6 address (deprecates AAAA) */
 	ns_t_dname = 39,	/* Non-terminal DNAME (for IPv6) */
-	ns_t_sink = 40,		/* Kitchen sink (experimentatl) */
+	ns_t_sink = 40,		/* Kitchen sink (experimental) */
 	ns_t_opt = 41,		/* EDNS0 option (meta-RR) */
 	ns_t_apl = 42,		/* Address prefix list (RFC 3123) */
 	ns_t_tkey = 249,	/* Transaction key */