Default value for Compiler macros

[f3l1x]

• bug report? no
• feature request? yes
• version: 2.4.x

Description

We're writing template processing with Latte\Engine. We have defined our custom Compiler and it has ho macros. At this time it's not possible, because Compiler::$macros has no default value.

I'm not sure it's bug a or feature (Compiler could live without any macro?).

I can prepare PR in case.

[dg]

PR would be fine

[f3l1x]

Closed via #177