Wrap the tweet content into a span element with a CSS style attribute
set to "white-space: pre-wrap", this allows to have the spaces rendered
like on the twitter web page: with spaces and newlines preserved.
This is especially desirable if the tweet content contains any ASCII
art, like in https://twitter.com/sarahjeong/status/
955651919279722496
 
                     <xsl:text>(Video)</xsl:text>
                     <xsl:element name="br"/>
                 </xsl:if>
-                <xsl:apply-templates select="$item-content/node()"/>
+                <xsl:element name="span">
+                    <xsl:attribute name="style">white-space: pre-wrap;</xsl:attribute>
+                    <xsl:apply-templates select="$item-content/node()"/>
+                </xsl:element>
                 <xsl:apply-templates select="$item-media/node()"/>
                 <xsl:text disable-output-escaping="yes">]]></xsl:text>
             </description>