* Add global Lua function 'some'
Moved documentation for 'each' function to non-standard section.
* Revert "Add optional argument to template.each for empty collection output (#1359)"
This reverts commit b73dadec67.
* Reimplement #1359 using 'some' function
When omitted, the function outputs empty string for empty table as before.
The feature was motivated by the Maintenance page in v1 that showed messages
instead of just empty blocks (ported over).