What you're looking for is AviDemux.
AviDemux is an open-source GUI video processing software made in Linux which also has releases for windows (x86 and x64), it also has a commandline version called avidemux_cli.exe which comes inside the package.
It can perform re-conversion of various formats and also it can perform copy/cut/paste operations with no re-conversion, this mneans 0% quality is lost during the procedure because is just a remux operation.
It has a very user-friendly UI, and works perfect for cut/split a video once or at various points, as I said, with no reconversion unless you specify the opposite.
I love AviDemux, you will love it too. Download it here: