Ability to use space character in @ref code completion

#1

When entering @refs, as the user types out the string, code completion presents menus of anticipated options (which seems noticably faster lately :+1:).

However, upon typing a space character, code completion loses the plot and all menu options disappear :open_mouth:.

code_complete_spaces-1_2019-01-12_0923

code-complete-space-2_2019-01-12_0925