Adds gitignore file

[astralchan]

make will generate object files and, of course, the binary xmenu. When developing, people don't want to have to deal with make clean before pushing, adding a .gitignore file to your project will automatically ignore files when doing git operations like push, commit, merge, rebase, etc.

[phillbush]

Personally, I do not use .gitignore on my projects. For example, I use

git add -u

in place of

git add *

to add things already tracked into the index.

[astralchan]

Fair enough, contributors will then have to keep this in mind.