Undesired whitespace before *span* and *a*.

[m-e-leypold]

span and a also do not have the is_inline attribute set (similar issue as #139 and #194). This leads to unwanted white space (before the <a in the example) e.g. in

with span():
    text("(")
    with a(href=myurl):
        text("some")
    text(")")

[davetapley]

I assume related:
If I use an a without a with,
then I need to manually add a space at the start of a text immediately following the a.