Convert yml2 into a Python package.
* Rename yml2.py -> yml2/__init__.py
* Rename backend.py -> yml2/backend.py
* Rename pyPEG.py -> yml2/pyPEG.py
* Use relative imports where appropriate.
* Change imports in yml2c, yml2proc.
* Update make target `clean`.
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"><xsl:output method="xml"/><xsl:variable name="space" select="' '"/><xsl:param name="autoindent" select="4"/><xsl:param name="x"/><xsl:template match="/"><xsl:param name="_indent" select="0"/><html><head><title>Customer List</title></head><body><xsl:apply-templates select="list"><xsl:with-param name="_indent" select="$_indent+1*$autoindent"/></xsl:apply-templates></body></html></xsl:template><xsl:template match="list"><xsl:param name="_indent" select="0"/><table><xsl:apply-templates select="customer"><xsl:with-param name="_indent" select="$_indent+1*$autoindent"/></xsl:apply-templates></table></xsl:template><xsl:template match="customer"><xsl:param name="_indent" select="0"/><tr><td><xsl:value-of select="$x"/></td><td><xsl:value-of select="id"/></td><td><xsl:value-of select="name"/></td></tr></xsl:template></xsl:stylesheet>