[ticket/14994] Refactor template->assign_block_var
Refactor assign_block_var to use the same block selection mechanism
as is used in alter_block_array. This allows creating new blocks
at any position in the template structure, not only on the last block.
Allows selecting a block as outer[2].middle.
Added tests. Added PHP 7.2 compatibility.
[ticket/14994] Refactor template->assign_block_var
Refactor assign_block_var to use the same block selection mechanism
as is used in alter_block_array. This allows creating new blocks
at any position in the template structure, not only on the last block.
Allows selecting a block as outer[2].middle.
Added tests. Added PHP 7.2 compatibility.
[ticket/14994] Refactor template->assign_block_var
Refactor assign_block_var to use the same block selection mechanism
as is used in alter_block_array. This allows creating new blocks
at any position in the template structure, not only on the last block.
Allows selecting a block as outer[2].middle.
Added tests.