v1.2.0: Add C++ implementation of standard error calculations

 - Add C++ implementation of standard error calculations. This implementation
   uses SVD rather than a full pseudo-inverse.
 - Add argument `se.smooth` for experimental Laplace smoothing on the response
   probabilities when doing standard error calculations. This provides better
   numerical stability and avoids very small standard errors.
 - The original poLCA code is used for `nclass=1`
 - Bump to C++20
 - No OpenMP to stop overthreading in the regression model
 - Minor update to the documentation
 - Minor improvements in the C++ code by using more of the arma and C++
   features such as using in-place operations and containers instead of raw
   arrays

v1.1.1

Minor refactoring and bug fixes

• Fix missing #include <memory>
• Implement the sum of log probabilities in EStep(). This is only used when an
  underflow is detected
• Update README
• Add and update blrt scripts
• Add Doxyfile

v1.1.0

Add bootstrap likelihood ratio test

Add function blrt() which compares two
poLCA models together.

Minor adjustments to C++ code to cater
for blrt.

Minor adjustments to documentation.

v1.0.1

Debug usage of dependent packages

Correctly calls dependent packages using their namespace
se$b should be correctly outputted
Documentation using roxygen2
Include exec/ which compares with the original package

v1.0.0

Initial release