Text Rotation support

[ottomated]

Text rotations are defined in styles.xml like this:

<xf borderId="0" fillId="0" fontId="1" numFmtId="0" xfId="0" applyAlignment="1" applyFont="1">
  <alignment readingOrder="0" textRotation="135" />
</xf>

I believe a value of 255 means the text should be
s
t
a
c
k
e
d
like that.

[nhatcher]

This is doable. I will try to squeeze this in version 1.0