Remove uses of `print()`

[sprunk]

Spring.Echo exists but there's also a native Lua print() function which seems to do something similar. Having two functions that do the same thing introduces maintenance difficulties. Figure out if there are meaningful differences and replace its use in wupgets (keep in mind basecontent files won't be found via simple repo grep!). It's probably good to keep the function available though even if it's a 100% Spring.Echo equivalent because random modders might be familiar with it via general knowledge of Lua.