During export chart into .xlsx file,
the information about size of legend was not saved.
Example of proper size:
                    <c:w val="0.41459448854442293"/>
                    <c:h val="0.23161616722845749"/>
another issue was hardcoded "layoutTarget" which
was always "inner":
                    <c:layoutTarget val="inner"/>
also properties regarding default text style was not preserved:

            <c:txPr>
                <a:bodyPr/>
                <a:lstStyle/>
                <a:p>
                    <a:pPr>
                        <a:defRPr sz="900" b="0" i="0" u="none" strike="noStrike" kern="1200" baseline="0">
                            <a:solidFill>
                                <a:schemeClr val="tx1">
                                    <a:lumMod val="65000"/>
                                    <a:lumOff val="35000"/>
                                </a:schemeClr>
                            </a:solidFill>
                        </a:defRPr>
                    </a:pPr>
                    <a:endParaRPr lang="pl-PL"/>
                </a:p>
            </c:txPr>

With this patch all these issues was resolved, and in case
of layoutTarget "outer", the field is not availble at all,
according to specification.

Change-Id: I2c9b7a112bdd911542b5273e660222d7fefa2d88
Reviewed-on: https://gerrit.libreoffice.org/47358Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>