fbacchella/LogHub — pull request #1 by baloo (2014-08-10 10:46:13+00:00)
Title: Implement Reduce transformer

To avoid context switching, this transformer can reuse other
transformers

Like:
```
|
v
/---------------------\
| Add Field (thread1) |
\---------------------/
|
v
/------------------------\
| Change Field (thread2) |
\------------------------/
|
v
/-----------------------\
| Remove Field (thread3)|
\-----------------------/
|
v
```
to:
```
| /---------------------\
| /----| Add Field (thread1) |
| | \---------------------/
v |
/------------------\ | /------------------------\
| Reduce (thread1) |----+----| Change field (thread1) |
\------------------/ | \------------------------/
| |
| | /------------------------\
| \----| Remove Field (thread1) |
| \------------------------/
v
```