Added type restrictions to method args

Merge pull request #21 from konovod/patch-1

On Windows OS , use `webview.dll` and do a dynamic link. Thanks @konovod for this PR

Re-ordered overloaded methods to avoid Crystal bug

Merge pull request #18 from naqvis/update-webview

Updated webview library to latest version

Updated webview.h to its latest version

Updated for Crystal 1.0

Updated Makefile for Linux compilation

Updated for Crystal 0.36.0

Added Makefile to auto-compile object file

First Release