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[miguelportilla]

Fix such compile warnings as -Werror=non-virtual-dtor, -Werror=double-promotion. Errors that I have got during the compilation using the gcc 10.2.0 compiler.

error: implicit conversion from ‘float’ to ‘double’ to match other operand of binary expression [-Werror=double-promotion]
  123 |                 65536.0 * load_factor), 65535);

  error: implicit conversion from ‘float’ to ‘double’ to match other operand of binary expression [-Werror=double-promotion]
   85 |         static_cast<std::size_t>(65536.0 * loadFactor), 65535);

error: ‘class nudb::detail::store_base’ has virtual functions and accessible non-virtual destructor [-Werror=non-virtual-dtor]
   17 | class store_base

cc1plus: all warnings being treated as errors

[codecov[bot]]

Codecov Report

Merging #88 (0cd63d7) into master (c420c4c) will increase coverage by 0.13%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #88      +/-   ##
==========================================
+ Coverage   93.18%   93.31%   +0.13%     
==========================================
  Files          29       29              
  Lines        1893     1826      -67     
==========================================
- Hits         1764     1704      -60     
+ Misses        129      122       -7     

Impacted Files	Coverage Δ
include/nudb/detail/store_base.hpp	100.00% <ø> (ø)
include/nudb/impl/basic_store.ipp	87.43% <100.00%> (+0.03%)	:arrow_up:
include/nudb/impl/create.ipp	100.00% <100.00%> (ø)
include/nudb/impl/rekey.ipp	100.00% <100.00%> (ø)
include/nudb/detail/gentex.hpp	86.66% <0.00%> (-1.91%)	:arrow_down:
include/nudb/detail/format.hpp	95.07% <0.00%> (-0.98%)	:arrow_down:
include/nudb/detail/bulkio.hpp	88.88% <0.00%> (-0.40%)	:arrow_down:
include/nudb/detail/stream.hpp	95.23% <0.00%> (-0.22%)	:arrow_down:
include/nudb/verify.hpp	100.00% <0.00%> (ø)
include/nudb/basic_store.hpp	100.00% <0.00%> (ø)
... and 7 more

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