delete files specific to code editors (#120)

* delete files specific to code editors

* remove TwoFactorAuth.phpproj
* remove TwoFactorAuth.sln

They are not used anymore. See #119 (comment)

* remove deleted files from excluded files in composer.json

Author: NicolasCARPi

.gitattributes

@@ -10,5 +10,3 @@
 /multifactorauthforeveryone.png export-ignore
 /phpstan.neon export-ignore
 /phpunit.xml export-ignore
-/TwoFactorAuth.phpproj export-ignore
-/TwoFactorAuth.sln export-ignore