Remove the pserver, trainer, evaluators and some useless gradientmachines when compile mobile inference library.

* fix remote large update core

* wip

* working version

* fix style check

* fix style check

* update style check

related codes in Paddle core.

to create a gradient machine for inference using merged model with parameters
which is genearted by `paddle merge_model`.

Please use `override` not `virtual` in sub-classes.
`override` can check if there is a method in `parent` while compiling.

Make the evaluators inside a recurrent goup true evaluator, meaning that their evaluation results are incorporated into the whole evaluator result.

1. v2.layer.parse_network does not correctly handle the generation output.
2. GatherAgentLayer does not correctly handle generation output when batch_size > 1
3. Fix CustomStackTrace for rnn group

No longer need to use SubsequenceInput. The framework will detect.