return self from Element->compile()
assignment value is always an object
return self from extend->compile()
revert element->compile()
organize test data
more accurate line comparison
strictMath and strictUnits as static variables, simplify copyEvalEnv()
env->selectors not used
add 1.6.1 to test assets
parensStack as integer
$env not needed for toCSS() or genCSS()
$env not needed for sourcemap generation
$rule always has genCSS()
remove unused/dead code
declare Less_Functions->var and Less_Functions->currentFileInfo
use null for contrast() default args
Less_Tree_JavaScript->expression not ->evaluated
setFileContent() not set up for parse()
Less_Tree_Mixin_Definition() and Less_Tree_Mixin_Call() should not be called statically
remove unused $useBase64