mjpeg: Don't warn on unsupported image formats

When trying to start mjpeg compression mode, mjpeg_encoder_start_frame()
tests the image format as its only able to compress 24/32bpp images. On
images with lower bit depths, we return MJPEG_ENCODER_FRAME_UNSUPPORTED to
indicate this is not a format we can compress. However, this return goes
with a spice_warning("unsupported format"). As the rest of the code can
cope with this unsupported format by not doing mjpeg compression, it's
nicer to downgrade this spice_warning() to spice_debug().

This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1070028
Fix typo in log message
Fix test_capability() typo

It was spelt 'capabilty'
SpiceUserManual.xml: small clean-ups

Remove some non-conventional/non-freesoftware editor-specific lines.

Remove trailing whitespaces

Get rid of DTD, which is too strict for docbook, see also:
http://docbook.org/tdg5/en/html/ch02.html

This get rids of the following warning/error:

I/O error : Attempt to load network entity
http://docbook.org/xml/5.0/dtd/docbook.dtd
/home/elmarco/src/spice/spice-master/docs/manual/SpiceUserManual.xml:4:
warning: failed to load external entity
"http://docbook.org/xml/5.0/dtd/docbook.dtd"
          "http://docbook.org/xml/5.0/dtd/docbook.dtd">
                                                       ^
build-sys: simplify manual html generation
Associate org.spice-space.webdav.0 port to webdav channel

For example, with qemu, a webdav channel can be created this way:

 -chardev spiceport,name=org.spice-space.webdav.0,...

And redirected to a virtio port:

 -device virtserialport,...,name=org.spice-space.webdav.0
Translate docbook -> asciidoc

It's much much easier to read and edit, and the end results looks better
as well, see http://elmarco.fedorapeople.org/manual.html
manual: add folder sharing section
manual: fix xml highlighting
Update spice-common
Don't truncate large 'now' values in _spice_timer_set

static void _spice_timer_set(SpiceTimer *timer, uint32_t ms, uint32_t now)

The _spice_timer_set() function takes a 32-bit integer for the "now" value.
The now value passed in however, can exceed 2^32 (it's in ms and derived
from CLOCK_MONOTONIC, which will wrap around a 32-bit integer in around 46
days).

If the now value passed in exceeds 2^32, this will mean timers are inserted
into the active list with expiry values before the current time, they will
immediately trigger, and (if they don't make themselves inactive) be
reinserted still before the current time.

This leads to an infinite loop in spice_timer_queue_cb().

https://bugzilla.redhat.com/show_bug.cgi?id=1072700
Check RSA_generate_key_ex return value

This can fail in fips mode for example. If we ignore the failure, we'll get
a crash:

 #0  0x00007f38d63728a0 in BN_num_bits () from /lib64/libcrypto.so.10
 #1  0x00007f38d639661d in RSA_size () from /lib64/libcrypto.so.10
 #2  0x00007f38d7991762 in reds_handle_read_link_done () from /lib64/libspice-server.so.1
 #3  0x00007f38d7990c06 in spice_server_add_client () from /lib64/libspice-server.so.1
 #4  0x00007f38d7990c6a in reds_accept () from /lib64/libspice-server.so.1
 #5  0x00007f38dc0d2946 in qemu_iohandler_poll (pollfds=0x7f38dedce200, ret=755449965, ret@entry=1) at iohandler.c:143
 #6  0x00007f38dc0d6ea8 in main_loop_wait (nonblocking=<optimized out>) at main-loop.c:465
 #7  0x00007f38dbffd7c0 in main_loop () at vl.c:1988
 #8  main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:4357

This commit will cause the client connection to fail but qemu won't
segfault.
manual: improve text about ~/Public