Truncate all number arguments (closes #746); review usage of === undefined (closes #767); review handling of arguments of wrong type

[leshakoss]

• Convert number arguments into integer number using a custom toInteger implementation

• Change null/undefined/true/false implicit conversion strategy:

  • For required arguments:

  	date	number	string	boolean
  0	new Date(0)	0	'0'	false
  '0'	Invalid Date	0	'0'	false
  1	new Date(1)	1	'1'	true
  '1'	Invalid Date	1	'1'	true
  true	Invalid Date	NaN	'true'	true
  false	Invalid Date	NaN	'false'	false
  null	Invalid Date	NaN	'null'	false
  undefined	Invalid Date	NaN	'undefined'	false
  NaN	Invalid Date	NaN	'NaN'	false

  • For optional arguments, null and undefined are treated as if argument is not provided