bitbake: BBHandler/ConfHandler: Improve multiline comment handling

Faced with an expression like:

 # Some comment \
 FOO = "bar"

what should bitbake do? Technically, the \ character means its multiline and
currently the code treats this as a continuation of the comment. This can
surprise some people and is not intuitive.

This patch makes bitbake simply error and asks the user to be clearer
about what they mean.

(Bitbake rev: 589d31ce41e019ee6a7cb6527d67bc76c0b6382a)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
BBHandler/ConfHandler: Merge fix for multiline comments

This was meant to be squashed into the previous commit for multiline comment
handling. It fixes the case the commented multiline is followed by an empty
line which was resulting in a traceback instead of a sane error message.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
hob: progress bar changed to busy cursor when you open log file

-the first implementation for this bug used a progress bar, that is shown
during open file process; it revelead that the progress bar stops earlier
-now I have implemented using gtk.show_uri() method, that shows itself a
busy cursor when it opens a file;
-deleted the code for the first implementation

[YOCTO #2997]
Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
hob: Hob should display warnings generated during parsing

-now Hob catches the warnings generated during parsing, and after the parsing
is completed, if there are any warnings, it shows a bar that contains a message
with how many warnings has encountered, and a button "View warnings"
-when "View warnings" button is clicked, Hob shows a dialog with the warnings;
if there more than 1 warning, you can use "Previous" and "Next" button to see them

[YOCTO #3215]
Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>