Validate filters

**Listing of filters for validation**
ID	Name	Options	Flags	Description
`FILTER_VALIDATE_BOOLEAN`	"boolean"		`FILTER_NULL_ON_FAILURE`	Returns `TRUE` for "1", "true", "on" and "yes". Returns `FALSE` otherwise. If `FILTER_NULL_ON_FAILURE` is set, `FALSE` is returned only for "0", "false", "off", "no", and "", and `NULL` is returned for all non-boolean values.
`FILTER_VALIDATE_EMAIL`	"validate_email"			Validates value as e-mail.
`FILTER_VALIDATE_FLOAT`	"float"	`decimal`	`FILTER_FLAG_ALLOW_THOUSAND`	Validates value as float.
`FILTER_VALIDATE_INT`	"int"	`min_range`, `max_range`	`FILTER_FLAG_ALLOW_OCTAL`, `FILTER_FLAG_ALLOW_HEX`	Validates value as integer, optionally from the specified range.
`FILTER_VALIDATE_IP`	"validate_ip"		`FILTER_FLAG_IPV4`, `FILTER_FLAG_IPV6`, `FILTER_FLAG_NO_PRIV_RANGE`, `FILTER_FLAG_NO_RES_RANGE`	Validates value as IP address, optionally only IPv4 or IPv6 or not from private or reserved ranges.
`FILTER_VALIDATE_REGEXP`	"validate_regexp"	`regexp`		Validates value against `regexp`, a Perl-compatible regular expression.
`FILTER_VALIDATE_URL`	"validate_url"		`FILTER_FLAG_PATH_REQUIRED`, `FILTER_FLAG_QUERY_REQUIRED`	Validates value as URL (according to » http://www.faqs.org/rfcs/rfc2396), optionally with required components. Note that the function will only find ASCII URLs to be valid; internationalized domain names (containing non-ASCII characters) will fail.

Note:
Numbers +0 and -0 are not valid integers but validate as floats.