GL: shader compilation w/ #include, Gettext++

- ozCore
  * String::fileDirectory() fixed
  * Gettext
    + catalogue strings loaded by directly copying strings block from file,
      including catalogue descriptions
    + catalogueDescriptions()
- ozEngine
  * GL: compileShaderFromFile(), handles #include directives
- glsl
  * #include directives added for header.glsl
- ports
  * freetype updated to 2.5.0.1