Fix bugs for rnn generation.

Handle multiple processes trying to create the data home directory

Add an order switch to xmap_readers

Rewrite tutorial comments in generic.cmake

ENH: Merge multiple static libs into singe one

Fix unit test error: File exists: '/root/.cache/paddle/dataset'

FIX: Add boost inc dir

Add WITH_GOLANG to control the link of go lib

Allow printer layer to print user-provided message

Move paddle/majel/* to paddle/{platform,framework/*

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

For example:
layer.printer(input=[x, y], format="x=%s y=%s")

Fix some compile error.

merge with lasted develop branch. Optimizer lib2

Repeat layer for column vector