moved IConsole to ScriptCs.Contracts
extended IScriptExecutor with Initialize and Terminate, refactored accordingly
moved Repl to ScriptCs.Core and derived it from ScriptExecutor to prevent code duplication
refactored ScriptExecutorTests to reflect the new structure
added possibility to get full path from filesystem to facilitate #r loading in REPL
Merge branch 'dev' of https://github.com/scriptcs/scriptcs into repl-refactor

Conflicts:
	src/ScriptCs.Core/IScriptExecutor.cs
	src/ScriptCs.Core/ScriptExecutor.cs
	src/ScriptCs/Command/ExecuteScriptCommand.cs
	test/ScriptCs.Core.Tests/ScriptExecutorTests.cs
	test/ScriptCs.Tests/ExecuteScriptCommandTests.cs
Merge pull request #290 from filipw/repl-refactor

Repl changes to unify with ScriptExecutor