#1 Multiple fixes in one PR

Separated by commits: First commit is not a functional change, just whitespace changes: - Change all tabs to spaces to make whitespace usage consistent (spaces and tabs were used inconsistently). - Canonicalize newlines to LF as git expects, in order for system-specific line endings to work (a file was imported with CR/LF in Linux). - Remove extra spaces at the end of some lines. Second commit simplifies a lot of the code (and makes it faster) by removing repetitions of `minetest.registered_nodes[...]`. Third commit adds `palette` to the copied node properties. The next three commits are bugfixes: - Lava sources caused a crash in the client, because the `liquidtype` property wasn't copied and that triggered an assertion failure. - There was a bogus warning when `intllib` wasn't defined. - A light intensity of 15 is not valid and was triggering a warning. Maximum intensity is 14.