Lazy Array implementation

[haberdashPI]

Trying out an implementation approach that uses lazy arrays, and requires
all signals to be arrays.

Benefits:

1. simplify the implementaiton
2. Speed it up: arrays are really fast in julia and my streaming chunks turned out to be slow for some use cases; the use of Mmap'ed arrays would allow handling use-cases with
   large data. The only thing this prevents is streaming data, and that isn't a great use of julia right now anyways

Steps to implement

• basic operations draft implementation (all but reformatting and ramps)
• test basic operations
  • types
    • numbers
    • arrays
    • functions
  • operations
    • cutting
    • appending
    • padding
    • filters
    • mapping
• test the speed of the implementation
• then add more advanced features