Ahk

Adds safeguards and warnings for instantiating ahk with `executable_path`

added method find_window_by_class (and its generator) + class_name property (thanks Pestitschek)

Minor release. Includes fix of return value for some functions. 60

Adds modifier options for image search. 59

Adds sound features

sound_beep
sound_play
sound_get
get_volume
sound_set
set_volume

Adds keyboard support! Defines the following functions

* key_state
* key_wait
* type
* send
* send_raw
* send_input
* send_play
* send_event
* key_press
* key_release
* key_down
* key_up

Other changes:

Hotkeys moved to keyboard module
keys module

debugging/logging instructions now accurate
suppress StopIteration error when using find_windows* functions when window not found

Fixes relative mouse drag
Adds screen functions:
image_search
pixel_search
pixel_get_color
Windows are hashable & equality comparable
ahk.windows() no longer a generator; returns a list

Adds preliminary functionality for

* `Hotkey`s
* `ActionChain`s
* `win_set`