Adapt WUI library to use lenses and the ideas behind 'Lenses for Web Data'

Unfortunately, the current definition of a `WuiSpec` cannot be used to transform specs withs lenses, because an inital value is missing.
Extend representation of wui specification

Reuse the old `WuiSpec a` defintion for the new representation `type WuiLensSpec a = Maybe a -> WuiSpec a`. An optional intial value can be passed for each specification instead of the explicit value that is passed by the generation of the form. With this optional value, `transformWSpec` can be defined with lenses: `transformWSpec :: Lens a b -> WuiLensSpec a -> WuiLensSpec b`.
Furthermore, the examples in `FormLenses.curry`  are adopted to fit the new WUI interface.
Fix path to curry modules in base directory
Use WUILenses instead of WUI for testing purposes
Adopt initialisation of WUI to fix error cases

`showAndReadWUI` takes an initial value, otherwise it could pass `transformWSpec` `Nothing`, which will yield `failed` for every usage of `put`.
Make it compile again (inappropriate `where`)
Adjust type signatures and partial appliication of some functions
Fix local definition of `newVars` in function `wMultiCheckSelect`

The local defintion is not appropriate since `newVars` is a constant (with a recursive call) and, therefore, every variable is evaluated to the same value, which is not the intended behaviour.
Adapt Spicey example to use WUILenses

Exchange all uses of WUI to WUILenses and add some special edit views to test the usage of `transformWSpec` in order to hide entity information.
Remove redundant import
Update README and notes
Clean up code
Add new implementation of lenses

This implementation allows to only define put-based lenses and the corresponding `get` function is defined in terms of `put`. The defintion of `get` is generated by the builtin-search. Nevertheless, not every put-based lens definition has only one corresponding `get`, therefore, we use a helper function to check, if only one result is generated.
Adapt WUI specification to work with  and adjust WUI examples
Restructure module for lens examples and add an additional module to test these lenses
Add question about Spicey Framework
Restructure directory
Adapt examples for combinatorial lens implementation

Merge individual examples .curry-files into LensExamples.curry and helper functions into MonadicExamples.curry
Clean up repository

Organize the two different implementations in directories `PutLenses` and `CombinatorialLenses`. For a better testing suite, rename both module to `Lens`. All other modules that depend on a lens implementation import `Lens` now, the wished implementation has to be specified in `CURRYPATH`.
Make Spicey Blog examples usable with both implementations

An extra module for Blog-specific lenses (`BlogLenses`) is part of both implementations and the Blog example imports `Lens` and `BlogLenses`, the concrete implementation is given by path declaration.