Add function array_cast<T>
Simplify template. These complicated templates cannot be compiled with VS2012
Use operator= overloading instead of assign function for lazy array
operator+ overloading
Apply operator overloading of lazy array to circularize example
Fix compile error with VS2012
Return false if imread fails
Add copy constructor/assign of array_t (shallow copy)
Add default constructor of base_array_t to use map
Assign base_array_t to array_t (assert type)
minor
Add function array_at(index)