CoralVM-PHP: Adding constant for implicit expressions

Implicit expressions are a new abstract term. Explicit expressions are those denoted explicitly by parentheses (or keyword and complex parentheses), implicit expressions, on the other hand, are implied from their context. Basically it means arguments passing in "poetry-mode" known from Ruby. Tokenizer will recognize these based on a look-behind.
CoralVM-PHP: Expression lists and identifier nodes of AST now carry "implicitness" flag
CoralVM-PHP: Adding expression node

This is for expressions that are only expressions, without specification. Includes implicit and explicit expressions. These nodes evaluate to the value of their last node (and execute all previous nodes as well).
CoralVM-PHP: Adding procedure node
CoralVM-PHP: Updating operator node to correctly handle "binary not" operator with secondary meaning
CoralVM-PHP: Extending abilities of root AST nodes
CoralVM-PHP: Removing implementation of precedence of token layers
CoralVM-PHP: Updating phpdoc of tokens
CoralVM-PHP: Updating tokenizer to correctly recognize implicit expressions
CoralVM-PHP: Fixing token-layer-to-expressions to discard parentheses
CoralVM-PHP: Updating debug output of function body AST managers
CoralVM-PHP: Updating method call nodes with correct handling of procedures hidden in arguments

Procedures are now adopted from arguments while arguments are added: low-priority procedures are extracted recursively from expression, expression list and method call nodes, high-priority procedures are extracted directly without recursion.
CoralVM-PHP: Fixing operator node to work correctly with method call nodes
CoralVM-PHP: Updating expression-to-node manager methods to handle explicit and implicit expressions
CoralVM-PHP: Removing no longer used recursive methods from expression-to-node manager