Accept hostname targets that do not contain a period.

This fixes issue #123, which was due to a misinterpretation of the
line

`if host.split(".")[0][0].isalpha() or host.split(".")[-1][-1].isalpha():`

(see commit 8d46d14731, L156). Because of
how Python's str.split() works, a hostname that does not contain a
period when .split(".") results in a single-item list, so this
expression evaluates to True. However, this also means that the
.split()s had no effect: the line was equivalent to

`if host[0].isalpha() or host[-1].isalpha()`.

Interlace/lib/core/input.py

@@ -187,10 +187,7 @@ class InputHelper(object):
             for target_spec in target_specs:
                 if (
                     target_spec.startswith(".") or
-                    (
+                    (target_spec[0].isalpha() or target_spec[-1].isalpha()) or
-                        (target_spec[0].isalpha() or target_spec[-1].isalpha())
-                        and "." in target_spec
-                    ) or
                     (nocidr and "/" in target_spec)
                 ):
                     str_targets.add(target_spec)