Add skeleton/plan for LCU based search.

The plan is to replace the dumb search we are doing now with proper sequential
search that is encapsulated inside data structure that holds all temporary
search data for the LCU.
Add lcu_t initialization.
Implemented proper intra mode cost calculation

This does not currently affect the search primary search defining the used block sizes, only the refining second intra search. Gain 1.9% BD-rate on All Intra 600f of BQMall QP 22,27,32,37.
Implemented intra_recon_lcu() to reconstruct intra in the new structure
Modified intra_build_reference_border() to work on the new structure
Modified intra_prediction() to use new structure and renamed intra_merge_cost()
Modified intra_get_dir_luma_predictor() to use the new structure

Also fixed intra_pred_ratecost() parameters and usage of intra_build_reference_border()
Fixed intra headers and implemented intra search in the new structure
Modified encode_transform_tree() to use new structure
Fixed problems with the new structure and commented out old search
Fix compilation for rebase.

Conflicts:
	src/search.c
Add lcu_t copying to main CU array.
Add work_tree_copy_up.
Fixed coeff flag derivation from NxN blocks
Add work_tree_copy_down.
Fixed cu type definition and reconstruction function calling

reconstruction could have been called when no search was done
Intra fix: encode_transform_tree() call was missing and depth was not set
Fixed allocated size for coefficient arrays
Add copying of LCU coefficients to search.
Remove unnecessary copying of reconstructed pixels from init_lcu_t.

The reconstructed pixels don't exist yet.