Fix typos

Author: kojix2

lib/gr.rb

@@ -137,7 +137,7 @@ def inqdspsize
     #  * 371       : Gtk
     #  * 380       : wxWidgets
     #  * 381       : Qt4
-    #  * 382       : Scaleable Vector Graphics (SVG)
+    #  * 382       : Scalable Vector Graphics (SVG)
     #  * 390       : Windows Metafile
     #  * 400       : Quartz
     #  * 410       : Socket driver
@@ -519,7 +519,7 @@ def inqlinecolorind
       inquiry_int { |pt| super(pt) }
     end
 
-    # Specifiy the marker type for polymarkers.
+    # Specify the marker type for polymarkers.
     #
     # @param style [Integer] The polymarker marker type
     #  * 1   : MARKERTYPE_DOT             - Smallest displayable dot

lib/gr3.rb

@@ -288,7 +288,7 @@ def createindexedmesh(num_vertices, vertices, normals, colors, num_indices, indi
     #
     # This function does not return an error code, because of its asynchronous
     # nature. If gr3_getpixmap_() returns a GR3_ERROR_OPENGL_ERR, this might be
-    # caused by this function saving unuseable data into the draw list.
+    # caused by this function saving unusable data into the draw list.
     #
     # @param mesh       [Integer]       The mesh to be drawn
     # @param n          [Integer]       The number of meshes to be drawn