Attempted to implement lazy loading of languages data

[sarthakmadaan]

Attempted to implement lazy loading to resolve issue #253 .

[codecov-io]

Codecov Report

Merging #294 into master will increase coverage by 0.38%.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           master   #294      +/-   ##
========================================
+ Coverage   97.61%    98%   +0.38%     
========================================
  Files          20     20              
  Lines        1674   1650      -24     
========================================
- Hits         1634   1617      -17     
+ Misses         40     33       -7

Impacted Files	Coverage Δ
dateparser/utils/__init__.py	98.09% <ø> (-0.14%)	⬇️
dateparser/languages/detection.py	100% <100%> (ø)	⬆️
dateparser/conf.py	97.91% <100%> (ø)	⬆️
dateparser/date.py	97.61% <100%> (+1.54%)	⬆️
dateparser/languages/validation.py	100% <100%> (ø)	⬆️
dateparser/languages/loader.py	96.61% <100%> (+10.24%)	⬆️
dateparser/languages/__init__.py	100% <0%> (ø)	⬆️

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[sarthakmadaan]

I checked the times of importing of dateparser in current system and after making changes.

Current :

>>> import timeit
>>> timeit.timeit('import dateparser',number=1)
1.249682903289795

After making changes :

>>> import timeit
>>> timeit.timeit('import dateparser',number=1)
0.6022160053253174

[sarthakmadaan]

@waqasshabbir could you please have a look at this PR. I have implemented on-demand loading of languages data and avoided loading at import time to reduce import time and have better performance in long run.

[waqasshabbir]

We must not mix data loading logic with this class here especially when we can completely avoid it by making necessary changes in LanguageDataLoader class.

[sarthakmadaan]

Thanks for the review @waqasshabbir . I have made required changes to implement loading logic entirely in LanguageDataLoader.

[dposada]

What's the status of this? I would love to take advantage of the speedup