Switched from buffer names to buffer numbers.

Also made psearch work with any type of buffer(except open command line
buffer)
Merge pull request #8 from someboddy/use-buffer-numbers-instead-of-names

Switched from buffer names to buffer numbers.
Update version and changelog
Do not open the psearch window along with an unnamed buffer
Fix the buffers() function to return only named buffer
Open the psearch window as soon as the :PSearch command is triggered
Closes #9
Remove unused code
Refactor the "buffer_with_matches" method
Remove unused module import
Change default characters
Simplify plugin initialization
Update README.md
ctrl-u to clear the current input
clean the last founded matches
update the readme a bit
Merge pull request #12 from Aaron2Ti/dev

ctrl-u to clear the current input
Update changelog and version