[add] Reciprocal operation

Context

Closes #324 (closed)

Major modifications

• add: Reciprocal operation
  • Operator core definition
  • Python binding
• ArrayHepler.hpp: add constructors to ArrayND
  • add: delete default constructors
  • add: constructor from value
  • add: constructor from 1d C-style array
  • add: constructor from nd C-style array