add an option to CLI tool for reporting annotation by line and column number

fixes issue #162.
In the mentioned issue there is a need for reporting annotation with line and column number, in order to make them more readable for human to debug their code.
In this PR a function has been added [`snowcrash.cc`](https://github.com/alikh31/snowcrash/commit/d8397c2e1b6f7bcc74b3a9357284231408dd93d3#diff-6a5a8e0ab7a5b957ab294981f601a3d4R42) to convert character map into line number, in order to do so there is the need of passing the blueprint source string to the mentioned function for being able to count the lines and columns accordingly. inside the function by two `for` loop the function returns the starting and ending of character map + length.
There are also some notation fix for `snowcrash.cc` for constancy of the code in compare with snowcrash library.

@pksunkara it's not traversing the whole source for each warning/error but up to the ending point of the warning/error but anyway you are right, it's not the most optimized way to do it. but doing it in other ways would make the code more complicated and reduce readability, if you think that the right approach I can fix it to something with a better performance.