Remove spaces in end-of-line.
Fix Numeric#pow behavior.

 * Before

2 ** -1 #=> 0

 * After

2 ** -1 #=> 0.5
Add test for Numeric#pow.
Merge pull request #2562 from cubicdaiya/issues/pow_flo

Fix and add test for Numeric#pow behavior.
Merge pull request #2561 from cubicdaiya/issues/space_EOL

Remove spaces in end-of-line.
Merge branch 'master' into iij