support tab stops

[wangfengming]

Enhancement: Support tab stops for paragraph

#810

[gitbrent]

Hi @wangfengming - Can you provide some test cases and examples of the output?

[wangfengming]

@gitbrent
#810

<a:p>
    <a:pPr>
        <a:tabLst>
            <a:tab pos="2879725" algn="l"/>
            <a:tab pos="5760085" algn="l"/>
            <a:tab pos="8639810" algn="l"/>
        </a:tabLst>
    </a:pPr>
    <a:r>
        <a:rPr lang="en-US"/>
        <a:t>a	b	c	d</a:t>
    </a:r>
</a:p>

new tag is: <a:tabLst>.
the str in <a:t> tag is a\tb\tc\td, \t is tab.

[gitbrent]

Thanks @wangfengming !

Implemented via Pull #943 (it did not auto-relate to this Pull for some reason)