add macros support

Macros should be declared as `aw_macro<name,arg1,arg2,...>{{macro body}}` and then
they may be used as `aw_name<arg1,arg2,...>{{}}`. It just puts `macro
body` to pattern and replaces arguments to provided ones according to
macro call. E.g.:
```
$aw_macro<test,phrase>{{phrase}}$aw_test<hello world>{{}}
```
will transform into
```
hello world
```

sources/awesome-widget/plugin/awpatternfunctions.h

@@ -43,6 +43,7 @@ QString insertAllKeys(QString code, const QStringList keys);
 QString insertKeyCount(QString code, const QStringList keys);
 QString insertKeyNames(QString code, const QStringList keys);
 QString insertKeys(QString code, const QStringList keys);
+QString insertMacros(QString code);
 // find methods
 QStringList findKeys(const QString code, const QStringList keys,
                      const bool isBars);