Revert "gvariant: Fix confusion between type and format strings in the docs"

This reverts commit fca1b83be74c9840037cfee84015fd8460cc33f9.

The original documentation was correct.

https://bugzilla.gnome.org/show_bug.cgi?id=729269
gio tests: rm xdgconfighome on 'make clean'
GLib 2.41.0
gio/tests/network-address: fix when no network is available

GResolver doesn't do full validation of its inputs, so in some of
these tests, the fact that we were getting back
G_RESOLVER_ERROR_NOT_FOUND is because the junk string was getting
passed to an upstream DNS resolver, which returned NXDOMAIN. But if
there's no network on the machine then we'd get
G_RESOLVER_ERROR_INTERNAL instead in that case.
mapping-test: Add debug spew

This might help figuring out why the test is failing in continuous.
gvariant: Clarify type and format strings in the docs

'@' and '&' are only used in format strings as prefixes to type
strings and not to full format strings.

https://bugzilla.gnome.org/show_bug.cgi?id=729269
Add more debug spew to the mapping-test
gconvert: mention that the g_convert len should be in bytes

Some charsets have each char with more than one byte, make it clear that
the length should be in bytes

https://bugzilla.gnome.org/show_bug.cgi?id=730963
Fix the mapping test in continuous

It turns out that due to a recent gdm change, the inherited
signal mask has SIGUSR1 blocked - which is bad news for
tests using SIGUSR1. Fix the test by explicitly checking the
signal mask before using SIGUSR1.
Fix the closure test in continuous

This test has the same problem as the mapping-test - it uses
SIGUSR1 without checking the signal mask. Apply the same fix
here.
gtype: Add check for fundamental instance type

When checking whether an instance is of a given fundamental type (such
as G_TYPE_OBJECT), we can avoid over 60%+ of the cost of checking types.

https://bugzilla.gnome.org/show_bug.cgi?id=730984
gobject: Use fast fundamental instance type check

Speeds up g_object_ref/_unref by 50%-65% (i.e. takes 60-65% of the time
it used to take).

https://bugzilla.gnome.org/show_bug.cgi?id=730984
GParamSpec: Use new fundamental instance check

https://bugzilla.gnome.org/show_bug.cgi?id=730984
docs: Add a 2.42 api index
docs: Add some missing apis
docs: Fix up varargs documentation

gtk-doc expects varargs to be documented in a specific way,
otherwise it complains.
Document g_signal_handlers_destroy
docs: Fill in gshell long description
docs: Fill in the gspawn long description
Minor documentation additions and corrections

Going for 100%.