text: use a different invisible character for text embedding

Contributes to the work of @temetherian in #170

CHANGELOG.md

@@ -8,6 +8,7 @@ Features:
 
 Bugs:
 * Fresh installs of Squib were broken due to two hidden dependencies, gio2 and gobject-introspection. (#172)
+* Embedding icons in text show unicode placeholders on some OSs. This is a workaround until we get a better solution for embedding icons. See #170, #171, and #176. For that matter, see #103, #153, and #30 if you really want the whole story.
 
 ## v0.10.0 / 2016-05-06
 

lib/squib/graphics/text.rb

@@ -86,7 +86,7 @@ module Squib
         spacing = rule[:box].width[@index] * Pango::SCALE
         kindex   = clean_str.index(key)
         kindex   = clean_str[0..kindex].bytesize # byte index (bug #57)
-        str = str.sub(key, "\u0091<span letter_spacing=\"#{spacing.to_i}\">\u0091</span>\u0091")
+        str = str.sub(key, "\u2062<span letter_spacing=\"#{spacing.to_i}\">\u2062</span>\u2062")
         layout.markup = str
         clean_str     = layout.text
         searches << { index: kindex, rule: rule }