Fix expension of macros in pointers with default values.

For example :

in xsl decl widget_class(%name, *clsname="%nameWidget", match="widget[@type='%name']", mode="widget_class") alias template {
| class `text **clsname` extends Widget{
content;
| }
};

widget_class('Input');

gives now :

<xsl:template match="widget[@type='Input']" mode="widget_class">
<xsl:text>class </xsl:text>
<xsl:text>InputWidget</xsl:text>
<xsl:text> extends Widget{
</xsl:text>
<xsl:text>}
</xsl:text>
</xsl:template>

Without the fix, <xsl:text>InputWidget</xsl:text> would be <xsl:text>%nameWidget</xsl:text>

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[sdist]

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formats=gztar

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[metadata]

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name         = yml2

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version      = 2.7.0

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author	     = Volker Birk

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author_email = vb@pep-project.org

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url	     = https://pep.foundation/dev/repos/yml2/

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license	     = GPL v2

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license_file = gpl-2.0.txt

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[options]

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packages = yml2

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scripts =

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    yml2c

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    yml2proc

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include_package_data = True

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zip_safe = False

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install_requires = lxml