Lazy file

[jiangyi15]

memmap for npy file, it can reduce memory useage.
And option for Dataset.prefetch.
mv cp_trans to preprocessor

data:
    phsp: [phsp.npy] # only support npy file
    lazy_call: True 
    lazy_file: True # bool
    lazy_prefetch: 2  # int , -1 for auto, 0 for no, >0 for exact value

[codecov]

Codecov Report

Merging #105 (691ea2f) into dev (5a7ef7e) will increase coverage by 0.07%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##              dev     #105      +/-   ##
==========================================
+ Coverage   75.84%   75.91%   +0.07%     
==========================================
  Files         108      108              
  Lines       15559    15611      +52     
  Branches     2920     2927       +7     
==========================================
+ Hits        11800    11851      +51     
  Misses       3067     3067              
- Partials      692      693       +1     

Flag	Coverage Δ
unittests	75.91% <83.33%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
tf_pwa/amp/preprocess.py	92.23% <75.00%> (-0.77%)	⬇️
tf_pwa/data.py	78.20% <76.92%> (+2.09%)	⬆️
tf_pwa/cal_angle.py	76.03% <100.00%> (+0.11%)	⬆️
tf_pwa/config_loader/data.py	64.63% <100.00%> (-0.34%)	⬇️
tf_pwa/tests/test_full.py	100.00% <100.00%> (ø)