The reason for adding the function is exemplified in the following hypothetical code:

mem = memory(name=None, size=256)
hidden = fc_layer(input=mem)
state = hidden + x
mem.set_input(state)

In the above code segment, it would be very annoying if we require the user to provide
the name at memory() call because the layer name of state is automatically generated
and is not easy to set it.

Change-Id: I918bf1d3d5c26addd88a6f7021e98b3e0e9df494

* It gets wrong command line arguments before.

* math => layer_math
* Fix #903

The values for ____crf_layer_0__.w0 in python/paddle/trainer_config_helpers/tests/configs/protostr/test_cost_layers.protostr is not correct due to swapped height and width in config_parser

* Make float equal works well.
  * compare 0.01 and 0.009999999999 will return true.

out = w * input
where w is a parameter of size 1

Change-Id: Ife682d62323ceb1a20cbbf6269421b20a862d888

* Fix #436