fix gitignore: don't ignore certain patterns of subdirectories

the project has source code in paths like:

    tests/src/de/pokerth
    src/chatcleaner

which should not be ignored. To fix this, a slash needs to be added in
front of the files that actually should be ignored.

While at it:
- pokerth_server does not need to be ignored (it's generated in `bin/`,
  which is ignored already)
- ignore some project files (for the case Eclipse is used as IDE)

.gitignore

@@ -8,14 +8,15 @@ Makefile.pokerth_protocol
 Makefile.pokerth_server
 Makefile.pokerth_dbofficial
 bin/
-chatcleaner
+/chatcleaner
 lib/
 mocs/
 obj/
-pokerth
+/pokerth
 qrc_pokerth.cpp
 uics/
 make.sh
 gitpush_serverstuff_stable
-pokerth_server
 .vscode/
+.project
+.classpath