directory and filenames should be capitalized under linux

[michaelfliegner]

ch9/caesar.hs should be Ch9/caesar.hs
ch11/vigenere.hs should be Ch11/Vigenere.hs

otherwise cabal complains, it can't find them

[michaelfliegner]

mf@mf-vbox:/informatik/haskell/haskell-book-solutions$ stack clean
mf@mf-vbox:/informatik/haskell/haskell-book-solutions$ stack build
haskell-book-solutions-0.1.0.0: unregistering (local file changes: README.md haskell-book-solutions.cabal src/Ch11/Vigenere.hs src/Ch9/Caesar.hs src/ch29/Vigenere.hs)
Building all executables for `haskell-book-solutions' once. After a successful build of all of them, only specified executables will be rebuilt.
haskell-book-solutions-0.1.0.0: configure (lib + exe)
Configuring haskell-book-solutions-0.1.0.0...
haskell-book-solutions-0.1.0.0: build (lib + exe)
Preprocessing library haskell-book-solutions-0.1.0.0...
Preprocessing executable 'vignere' for haskell-book-solutions-0.1.0.0...
[1 of 3] Compiling Ch9.Caesar ( src/Ch9/Caesar.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/vignere/vignere-tmp/Ch9/Caesar.o )
[2 of 3] Compiling Ch11.Vigenere ( src/Ch11/Vigenere.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/vignere/vignere-tmp/Ch11/Vigenere.o )
[3 of 3] Compiling Main ( src/ch29/Vigenere.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/vignere/vignere-tmp/Main.o )
Linking .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/vignere/vignere ...
haskell-book-solutions-0.1.0.0: copy/register
Installing library in
/home/mf/informatik/haskell/haskell-book-solutions/.stack-work/install/x86_64-linux/lts-8.2/8.0.2/lib/x86_64-linux-ghc-8.0.2/haskell-book-solutions-0.1.0.0-HKdlJUBstiv3NGvNQtKgZE
Installing executable(s) in
/home/mf/informatik/haskell/haskell-book-solutions/.stack-work/install/x86_64-linux/lts-8.2/8.0.2/bin
Registering haskell-book-solutions-0.1.0.0...
mf@mf-vbox:~/informatik/haskell/haskell-book-solutions$