Devel, new version incomming, v0.4.0

This pull request suposes big important changes, becoming definitively the new version of APRIL-ANN. Take into account that changes in the order of computations has introduced minor differences in optimizers of ANNs. In CNNs this difference is more important.

The most important changes are:

- Matrix classes doesn't have a major order flag. They are created always following row-major order, and it is possible to change this order by transposing dimensions of the original matrix. Math operations has been re-implemented asking for the order of the data, and working properly depending in that.

- Tokens are automatically unwrapped when they are pushed from C++ to Lua, and automatically wrapped when they are taken in C++ bindings. For this behavior, use the name `AuxToken` when using macros `LUABIND_GET_*` or `LUABIND_RETURN`.

- A `LuaTable` class has been added to allow a direct communication between C++ and Lua without replicating in C++ the data stored in Lua. It is useful for options tables, or to get dictionaries as weight matrix dictionaries of ANNs in trainable package.

### Unstable changes

- Added `matrix.op.repmat` function.
- Added `matrix.ext.iterate` iterator.
- Added statistical distributions in `stats.dist`.
- Added `matrix.ext.convolution` and `matrix.ext.real_fftwh`.
- Added `Matrix<T>::convolution` method. It is in experimental stage, please,
  be advice to use them by your own risk.
- Because of the changes in `Image`, several classes in package `imaging` has
  been reviewed, consistent tests are necessary to merge with master branch.

### API Changes

- Removed major order differentiation in `matrix`.
- `tokens.matrix` **automatically** wraps `matrix` instances, from Lua to C++.
- `matrix` **automatically** unwraps `tokens.matrix` instances, from C++ to Lua.
- Added new methods to `AprilMath::Limits` class.
- Added `metrics.roc` for ROC computation.
- Added new `class` behavior taken from
  [Lua OOP-iter](https://github.com/pakozm/lua-oop-iter), in order to introduce
  more modularity in APRIL-ANN.
- New `april_doc` and `april_set_doc` API, works with values instead of strings.
- Added `table.values`, `table.ivalues`, `table.keys` and `table.ikeys`
  iterators.
- `matrix.dict` could store sparse and dense float matrices.
- Added `matrix.cholesky(...)` method.

### Bugs removed

- Solved bug at `matrix:max()` and `matrix:min()` methods.
- Removed memory leak at `SelectANNComponent::doBackprop()` method.
- Solved bug at `CopyANNComponent::doBackprop()` method, incorrect behavior for
  multi-dimensional matrices.
- Solved bug at `ZCAWhiteningANNComponent::doBackprop()` method was wrong.
- Solved bug in `stats.boot()` function, it wasn't correctly updated to new
  `class` functions.
- Solve bug in `trainable.supervised_trainer`, problem with smooth_gradients
  flag.
- Solved bug in trainable.lua `train_holdout:execute()` method, the pocket
  algorithm wasn't work with negative loss functions.
- Solved bug at class.lua, inifite loop when calling `class.is_a()`.
- Solved bug at autoencoder training.
- Solved bug in ROC computation.
- CUDA is working, time performance of convolutions needs a review.
- Solved bug in `constString` extract numeric methods which returns `false` when
  the extraction procedure ends up to the character after the last valid number.
- Solved bug at `Matrix<T>::div` and `SparseMatrix<T>::div` methods.

### C/C++

- Added `LuaTable` class to allow access of Lua tables from C++ code.
- Added TAR support in C/C++, allowing to use streams as the standard I/O
  objects in APRIL-ANN.
- Added `basics` namespace which stores almost all C/C++ code in `basics`
  packages.
- Simplified read/write of matrices using the new `StreamInterface` objects.
- Added new `StreamInterface` for input/output operations, with specializations
  for C files, C strings, Lua strings, GZIP files, ZIP files. Other
  specializations are easier to implement in the future.
- Added statistical distribution classes.
- Removed C stack trace in ERROR_PRINT and ERROR_EXIT when compiling without
  debug.
- `Image` class code has been reviewed to be more coherent with current `Matrix`
  class implementation.