feat: full syntax for strftime, close #177

- strftime syntax: <flags><width><modifier><conversion>
- new conversions: %n, %t
- fixed conversions: %N
- flags: _ ^ - 0 # :
- modifiers: E, O (ignored)

test/unit/util/underscore.ts

@@ -95,4 +95,17 @@ describe('util/underscore', function () {
       expect(_.isObject(2)).to.be.false
     })
   })
+  describe('.padEnd()', function () {
+    it('should default ch to " "', () => {
+      expect(_.padEnd('foo', 5)).to.equal('foo  ')
+    })
+  })
+  describe('.changeCase()', function () {
+    it('should to upper case if there is one lowercase', () => {
+      expect(_.changeCase('fooA')).to.equal('FOOA')
+    })
+    it('should to lower case if all upper case', () => {
+      expect(_.changeCase('FOOA')).to.equal('fooa')
+    })
+  })
 })