Add tests for searching decimal and lengths units

Added 2 new tests:

test_decimal_size test returns an error code when decimal numbers are
detected in width, height, or viewBox attributes. It is impossible to
create a pixel-perfect icon if its size does not fit into the pixel grid.

test_lengths_units returns an error code when any lengths units are set
in width, height, and viewBox attributes. This is protect the icon theme
from icons with mm, inch, and others grids.
Also, the test ban px units, because the pixel grid is a default units
for SVG.

A few tests have been renamed, and its description has been updated.

Makefile

@@ -54,22 +54,38 @@ test: test_short
 test-all: test_short test_long
 
 .PHONY: test_short
-test_short: test_renderer test_optimization test_svg_elems test_symlinks test_filenames
+test_short: test_rendering_glitches test_optimization test_svg_elems test_symlinks test_filenames test_decimal_size test_lengths_units
 
 .PHONY: test_long
 test_long: test_xml_struct
 
-.PHONY: test_renderer
-test_renderer:
-	# >>> Searching for icons with renderer bugs
+.PHONY: test_rendering_glitches
+test_rendering_glitches:
+	# >>> Searching for icons with rendering glitches
 	@! LC_ALL=C grep -E -rl --include='*.svg' \
 		-e 'd="[a-zA-Z0-9 -.]+-\.[a-zA-Z0-9 -.]+"' \
 		-e 'd="[a-zA-Z0-9 -.]+\s\.[a-zA-Z0-9 -.]+"' \
 		$(ICON_THEMES)
 
+.PHONY: test_decimal_size
+test_decimal_size:
+	# >>> Detecting decimal numbers in width/height/viewBox attrs
+	@! LC_ALL=C grep -E -rl --include='*.svg' \
+		-e '<svg[ ].*(width|height)="[0-9]+\.[0-9]*"' \
+		-e '<svg[ ].*viewBox="0 0 [0-9]+\.[0-9]+ [0-9]+(|\.[0-9]+)"' \
+		-e '<svg[ ].*viewBox="0 0 [0-9]+(|\.[0-9]+) [0-9]+\.[0-9]+"' \
+		$(ICON_THEMES)
+
+.PHONY: test_lengths_units
+test_lengths_units:
+	# >>> Detecting lengths units
+	@! LC_ALL=C grep -E -r --include='*.svg' \
+		-e '<svg[ ].*(width|height|viewBox)="[0-9]+(|\.[0-9]*)[a-z]+' \
+		$(ICON_THEMES)
+
 .PHONY: test_optimization
 test_optimization:
-	# >>> Searching for unoptimized icons
+	# >>> Searching for non-optimized icons
 	@! LC_ALL=C grep -E -rl --include='*.svg' \
 		-e '^<\?xml' \
 		$(ICON_THEMES)
@@ -89,13 +105,13 @@ test_symlinks:
 
 .PHONY: test_filenames
 test_filenames:
-	# >>> Searching for invalid filenames
+	# >>> Searching for invalid icon names
 	@LC_ALL=C find $(ICON_THEMES) -not -iregex '[-_/\.+@a-z0-9]+' -print \
 		-exec false '{}' +
 
 .PHONY: test_xml_struct
 test_xml_struct:
-	# >>> Searching for broken SVG icons
+	# >>> Searching for non-valid SVG files
 	@find $(ICON_THEMES) -type f -name '*.svg' \
 		-exec xmlstarlet validate --list-bad '{}' +