wrong behaviour of the search module indexing logic doesn't allow to find a c++ book by "c++" keyword

Issue Summary

Greetings,

We discovered a wrong behaviour of the search module indexing logic.
We created a web site which sells books. Book is a product content type and of course has title.
We have IT books about C++ and C#.

We found that it is impossible to find these books by "c++" or "c#". It doesn't work even if we enter "c++" in double quotes. In our situation it is very important because such keywords as "c++" or "c#" exists in titles and people would like to be able to find something when searching by "c++" or "c#".

The problem is that search module remove "+" and "#" characters when indexing content and when processing entered keywords. We would like to propose you a patch which fixes this issue. We remove these characters ONLY when they are encountered in the end of the word but not in the middle.

At the moment we do this for "+" and "#" characters only but we hope you can improve this patch and make it more general.