OTGEdit is a graphical user interface for Open Terrain Generator (OTG), TerrainControl (TC) and Minecraft Worlds (MCW). OTGEdit can be used to create, import, edit and generate worlds. OTGEdit can also convert schematic files to BO3's.
OTGEdit is a WinForms app and works for Windows only. If you're a Java coder who would like to port OTGEdit to Java, please let me know!
Wiki: http://openterraingen.wikia.com/wiki/OTGEdit
To package your worldpack as a mod see: https://github.com/PG85/WorldPacker
Virus scanner note
If you scan TCEE.exe using VirusTotal you will get 1 scanner reporting a virus, this is a false positive however, the files are 100% clean. If you look at the results of the scan you'll see that only the virusscanner "Qihoo" sees the file as a virus. However, Qihoo has been known to "cheat" on virusscans (see: http://vrworld.com/2015/05/04/qihoo-360-antivirus-cheating/). It automatically marks files that are not digitally signed by big companies as viruses, which means that small free-ware/open-source developers can have a big problem as even completely clean and harmless files are marked as viruses by Qihoo. Even the people at CurseForge tested and approved this file and you can test it yourself using every other virusscanner except VirusTotal, it's clean.
For a good article on how to check a file for viruses including testing for false positives see: http://lifehacker.com/397236/how-can-i-find-out-if-a-file-really-has-a-virus