Avoid subtracting num_exclude_bands twice in library mode

[rmargine]

Fixing the problem in library mode where num_exclude_bands was subtracted twice.
This was introduced in #19 trying to fix the fact num_bands wasn't defined in library mode.
The solution of #19 was to subtract num_exclude_bands in param_read, but param_read is run twice (in wannier_setup and wannier_run). Now, we set num_bands to the correct value (already subtracted) in wannier_lib.f90, but we do it before calling param_read, so this should be a fix both to the current problem and to the original problem of #19.

[codecov]

Codecov Report

Merging #170 into develop will decrease coverage by <.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #170      +/-   ##
===========================================
- Coverage    57.41%   57.41%   -0.01%     
===========================================
  Files           27       27              
  Lines        15573    15572       -1     
===========================================
- Hits          8942     8941       -1     
  Misses        6631     6631

Impacted Files	Coverage Δ
src/parameters.F90	77.54% <ø> (-0.01%)	⬇️

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