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(")")