Using C-Script (.wdl-Files), there is that limit with a maximum of 40 include code files. It exists independent of the engine edition, for everyone. If you use Lite-C (.c-Files) instead of C-Script, there is no such limit for any edition.

Lite-C Tut. 1 Lite-C Tut. 2 Lite-C Tut. 3 (en)
Shader Tutorial (ger)

http://www.slindev.com