Add second bound state support

Adds the support for a second bound state by introducing pseudo
components. Only the bound phase of the pseudo components is actually
used. Transport equations are solved on the other phases.
There are two variants:
A) Every component is doubled / gets a pseudo component
B) Every component but the first (salt) is doubled
Variant B) is useful for SMA-like binding models.
Add Bi-Langmuir binding model

Adds the Bi-Langmuir binding model which uses a second bound state. The
Bi-Langmuir model consists of two independent Langmuir binding models
acting on the two bound states. There is no exchange between the bound
states. The different bound states are considered as different types of
binding sites. Therefore, there are also no competivity effects between
this two types of sites.

Documentation is updated accordingly and a forward example is included.
Improve const correctness and params in isotherms

Adds "const" specifiers to many local variables in the isotherms.
Unifies the constructors of the isotherms (in some of them the call
to configure() was missing). The bounds in the parameter specs are
adapted to the given ones in the docs (e.g. strictness for lower bounds
on QMAX'es).
Add more debug output for VERIFY_ANALYTICAL_JAC

The deviation of the analytical Jacobian to the AD one is output in
every time step. The deviation is divided into column and particle
equations.
Fix error checking bug in fitColumn script

There was a bug in the error checking of the links of the fitData
struct. The error message contained the name of the parameter which is
not available at this point. The name was removed from the message.
Add forward example using ParallelComputing Toolbox

Adds a modified forward simulation example (single component Langmuir
breakthrough experiment). Here, many simulations are performed in
parallel using MATLAB's Parallel Computing Toolbox.
Make logScale adjustable per parameter in fitColumn

In the fitColumn script the logarithmic transformation of a parameter
is now controllable on a per-parameter level. The examples have been
adapted accordingly.
Add custom parameter transform to fitColumn script

The user can now specify a custom parameter transformation which can be
applied before or after the logarithmic transformation.
Improve strsplit workaround

Improves the strplit workaround by moving the custom strsplit function
to a private directory and renaming it to splitstring. The workaround
is now always used and no file renaming is required in the installCADET
script.

Fixes #8.