Merge branch 'num-features' of https://github.com/underscorediscovery/wren into underscorediscovery-num-features

test/core/number/log.wren

@@ -0,0 +1,3 @@
+System.print(3.log)        // expect: 1.0986122886681
+System.print(100.log)      // expect: 4.6051701859881
+System.print((-1).log)     // expect: nan

test/core/number/pow.wren

@@ -0,0 +1,4 @@
+System.print(2.pow(4))     // expect: 16
+System.print(2.pow(10))    // expect: 1024
+
+System.print(1.pow(0))     // expect: 1