Feature Request: Strict and loose mode

[hummerd]

It will be great to have option - mode: strict or loose. Strict mode is how it works now. In loose mode only check fields that is really dangerous to have not initialized. By dangerous I mean types that will cause errors on access to it:

type Some struct {
	Counter int        // it's ok not to init this (in loose mode)
	Lock    sync.Mutex // it's ok 
	Slice   []int      // it's ok 

	Map  map[int]int // it's not ok - writing to not initialized map panics
	Cond *sync.Cond  // it's not ok - access to not initialized pointer will panic
	W    io.Writer   // it's not ok - access to not initialized interface will panic
	Chan chan int    // it's not ok - writing to not initialized chan will hang
}