modeline-parse: parse set and : correctly

When `set` or `se` is found at the start of the modeline, it should stop parsing options after `:`.

When `modeline-parse` is called in the following file, it should _not_ recognize `tabstop=4` and `invalid_option=3`.
```
# kak: set indentwidth=0 tabstop=16: tabstop=4 invalid_option=3
```

More info: http://vimdoc.sourceforge.net/htmldoc/options.html#modeline

rc/detection/modeline.kak

@@ -88,7 +88,7 @@ define-command -hidden modeline-parse-impl %{
         # More info: http://vimdoc.sourceforge.net/htmldoc/options.html#modeline
         printf %s "${kak_selection}" | sed                      \
                 -e 's/^[^:]\{1,\}://'                           \
-                -e 's/[ \t]*set\{0,1\}[ \t]//'      \
+                -e 's/[ \t]*set\{0,1\}[ \t]\([^:]*\).*$/\1/'    \
                 -e 's/:[^a-zA-Z0-9_=-]*$//'                     \
                 -e 's/:/ /g'                                    \
                 | tr ' ' '\n'                                   \