[Enhancement] Full Support for Dynamic Shape

[hikettei]

Changes

Doing !reshape for DynamicShape

TEST> (!reshape (make-input `(N C H W) nil)
		(~ N C H W -> (* N C H) W))
{CPUTENSOR[float] :shape (LazyAxis: f(N C H) = (N*C*H) LazyAxis: W) :id TID2755206 
  :vec-state [maybe-not-computed]
    <<Not allocated: size=(LazyAxis: f(N C H) = (N*C*H) LazyAxis: W)>>
  :facet :input
  :belongs-to :memory-pool
  :requires-grad NIL
  :backward <Node: RESHAPETENSORNODE-T (A[BEFORE] B[AFTER] -> B[AFTER])>}

The shape of AbstractTensor is now given as a LazyAxis structure; which can contain S-expression. This feature is advantageous in networks where the batch-size changes frequently, as it allows operations to be performed without having to recompile. As for CNN, complex shape transmissions can be represented as reported in #132 .

(call (Conv2d 3 6 `(5 5)) (make-input `(N 3 25 25) :X))

is now a valid operation.