Changes

Summary

1. test: parse: calc: Fix test data (z-index isn't a length) (details)
2. calc: Check unit validity during parse (details)
3. test: parse: calc: Add invalid calc unit tests (details)

Commit a4d432e76e56d3f24f81fa7b50140220ead3bffe by Michael Drake test: parse: calc: Fix test data (z-index isn't a length)
	test/data/parse2/calc.dat (diff)
Commit 8ad13f1eb9a12acf82318a410765aa5fad4510e0 by Michael Drake calc: Check unit validity during parse
	src/parse/properties/utils.c (diff)
	src/parse/properties/utils.h (diff)
Commit c3802838b22e847759073891b6cf9390eb349304 by Michael Drake test: parse: calc: Add invalid calc unit tests
	test/data/parse2/calc.dat (diff)