Get back diff-match-patch to provide support for old third party consumers
Docs: Add create release on GitHub to releasing docs
docs: #pootle-dev IRC channel for developers
issues: add an issues quicklink and divert bugs

Divert bugs quicklink to githuv issues so that we don't have to rewrite
them all.
issues: remove bugday scripts

We haven't used these in ages and they rely on bugzilla to work.
issues: point to github issue numbers
issues: changes bugzilla reference to Github issues

And reword as needed
issues: correct bugnumber conflicts

Issues and PRs use the same number sequence.  Fix bug numbers that
migrated to a different issue number.
issues: adapt styleguide to use issues not bugs
issues: convert all :bug: to :issue:
issues: remove :bug: quicklink
docs: point python links to https
xliff2po: Add support to convert XLIFF files with .xliff extension

Fixes #3202.
placeables: Correctly insert at an existing parent if appropriate

At the end of a string (Case 2) the undo of a deletion of a placeable
(e.g. an XML tag) would be restored as plain text instead of part of
the existing tag. This is a reintroduction of bb04ce073 with updated
tests and error checking.
Simplify file discovery

This avoids a lot of unnecessary paths, while still allowing all ways
we expect it to work. This should help somewhat with startup performance
on both Linux and Windows.
Output xml declaration for Qt Linguist files (fixes #3198).

I tested multiple versions of lupdate with the following source file
(main.cpp):
  #include <QDebug>
  #include <QCoreApplication>

  int main(int argc, char *argv[])
  {
    QCoreApplication app(argc, argv);
    qDebug() << QString(QObject::tr("A String"));

    return app.exec();
  }

Invocation of lupdate:
$ lupdate main.cpp -ts de.ts

lupdate (5.3.1):
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE TS>
<TS version="2.1">
<context>
    <name>QObject</name>
    <message>
        <location filename="main.cpp" line="7"/>
        <source>A String</source>
        <translation type="unfinished"></translation>
    </message>
</context>
</TS>

lupdate (4.8.6):
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE TS>
<TS version="2.0">
<context>
    <name>QObject</name>
    <message>
        <location filename="main.cpp" line="7"/>
        <source>A String</source>
        <translation type="unfinished"></translation>
    </message>
</context>
</TS>

lupdate (4.8.1):
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE TS>
<TS version="2.0">
<context>
    <name>QObject</name>
    <message>
        <location filename="main.cpp" line="7"/>
        <source>A String</source>
        <translation type="unfinished"></translation>
    </message>
</context>
</TS>

lupdate (4.6.2):
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE TS>
<TS version="2.0">
<context>
    <name>QObject</name>
    <message>
        <location filename="main.cpp" line="7"/>
        <source>A String</source>
        <translation type="unfinished"></translation>
    </message>
</context>
</TS>
Remove workaround for lxml < 2.2.0 and update README.
README: Remove reference to old lxml versions
Bugfix: Properly check for language in RC files

Update the check for language in RC files to be ok if is globally set and
the actual block doesn't have one or is set locally with the correct one.
Bugfix: Properly append comments

Comments were not appended because of wrong variable name.