Template the row/column index type.

This allows the overflow checks to be performed on the user's desired type,
rather than forcing the user to check for overflow themselves.

We also distinguish the Index_ type from the line count (i.e, LineIndex);
the latter could be much larger and still warrants a big type.

Author: LTLA

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.14)
 
 project(eminem
-    VERSION 1.1.2
+    VERSION 1.1.3
     DESCRIPTION "Matrix Market parser"
     LANGUAGES CXX)