Support a modular approach to cinch

[charest]

Sample usage of new modular approach:

project(myproject)

if(NOT "$ENV{CINCH_SOURCE_DIR}" STREQUAL "")
  set(CINCH_SOURCE_DIR $ENV{CINCH_SOURCE_DIR})
elseif(EXISTS ${CMAKE_SOURCE_DIR}/cinch)
  set(CINCH_SOURCE_DIR ${CMAKE_SOURCE_DIR}/cinch)
endif()

include(${CINCH_SOURCE_DIR}/cmake/modular-cinch-main.cmake)
include(${CINCH_SOURCE_DIR}/cmake/modular-cinch-macros.cmake)

Fix #19.

[junghans]

Is there a way to have ProjectLists.txt to include modular-cinch-main.cmake to avoid duplication?

[junghans]

The name might be a bit too generic and easy to be confused with config/packages.cmake.

[junghans]

Add 2014-2017 to years.

[charest]

@junghans ProjectLists.txt can't really include modular-cinch-main.cmake, but I pulled the duplicated content into a new file called globals.cmake.