`<D-d>` fails for single character words in normal mode

First, thanks to all contributors for making this plugin what it is! This makes my VSCode experience much more pleasant. OK here's the bug report:

Describe the bug
CMD-D works well to select multiple words for multi-character words in both normal and insert modes, and it works in insert mode for single characters, but in normal mode, when the cursor is over a single character word and I push CMD-D, I can't get multiple cursors to display.

To Reproduce
Steps to reproduce the behavior:

1. Type a a a somewhere
2. Enter normal mode
3. Place cursor over an a
4. Type <CMD-D>
5. Observe lack of multiple cursors

Expected behavior
Multiple selections appear over all matching single character words

Screenshots

Environment (please complete the following information):

• Extension (VsCodeVim) version:
• VSCode version: 1.0.2
• OS: OSX 10.12.6

===UPDATE===

Even doing the replace on a single selected character is flawed because it searches for any instance of that character, rather than isolated instances of that character. Example in action:

Start by reproducing the CMD-D steps with a a a in normal mode, then trace the normal-mode handling for single-character words and the related replace behavior. Done means CMD-D creates selections for all isolated matching characters without selecting unrelated occurrences.