In many files there are header comments that contain an Author:
statement, supposedly reflecting who originally wrote the code.
In a large collaborative project like libvirt, any non-trivial
file will have been modified by a large number of different
contributors. IOW, the Author: comments are quickly out of date,
omitting people who have made significant contribitions.

In some places Author: lines have been added despite the person
merely being responsible for creating the file by moving existing
code out of another file. IOW, the Author: lines give an incorrect
record of authorship.

With this all in mind, the comments are useless as a means to identify
who to talk to about code in a particular file. Contributors will always
be better off using 'git log' and 'git blame' if they need to  find the
author of a particular bit of code.

This commit thus deletes all Author: comments from the source and adds
a rule to prevent them reappearing.

The Copyright headers are similarly misleading and inaccurate, however,
we cannot delete these as they have legal meaning, despite being largely
inaccurate. In addition only the copyright holder is permitted to change
their respective copyright statement.
Reviewed-by: NErik Skultety <eskultet@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

XSLT allows for two ways of generating the output of transformation.
Either implicit, which xsltproc prints to stdout and can be redirected
to a file using -o file. Or explicit, which means the stylesheet
contains <xsl:document> element which specifies where the output should
be saved. This can be used for generating more files by a single run of
xsltproc and -o directory/ can change the directory where the output
files will be stored.

devhelp.xsl is special in that it combines both options in one
stylesheet, which doesn't work well with -o:

xsltproc --nonet -o ./devhelp/ ./devhelp/devhelp.xsl ./libvirt-api.xml

Outputs 4 *.html files into ./devhelp but then tries to write to
./devhelp/ as a file (hence the I/O error) rather than writing output to
the fifth file devhelp/libvirt.devhelp.

This patch modifies devhelp.xsl so that all files are generated using
<xsl:document> element and -o directory/ can be used to override output
directory where those files are saved.

by running this command:
git ls-files -z | xargs -0 perl -pi -0777 -e 's/\n\n+$/\n/'
This is in preparation for a more strict make syntax-check
rule that will detect trailing blank lines.

  added devhelp docs support, based on libxml2 stylesheets
Daniel