.gitignore + disable in-source builds (#98)

.gitignore

@@ -0,0 +1,81 @@
+# Autogenerated files due to apparent VS2017 bug:
+#   https://gitlab.kitware.com/cmake/cmake/issues/16458
+*.dir
+x86
+x64
+
+# Modified from https://www.gitignore.io/api/vim,macos,linux,emacs,cmake,windows,sublimetext,visualstudio,visualstudiocode
+
+### CMake ###
+# These files are generated if an in-source build is attempted, even though
+# it's disallowed.
+CMakeCache.txt
+CMakeFiles
+
+### Emacs ###
+*~
+\#*\#
+/.emacs.desktop
+/.emacs.desktop.lock
+*.elc
+auto-save-list
+tramp
+.\#*
+
+### Linux ###
+.fuse_hidden*
+.directory
+.Trash-*
+.nfs*
+
+### macOS ###
+*.DS_Store
+.AppleDouble
+.LSOverride
+# Icon must end with two \r
+Icon
+._*
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+### SublimeText ###
+*.tmlanguage.cache
+*.tmPreferences.cache
+*.stTheme.cache
+*.sublime-workspace
+*.sublime-project
+sftp-config.json
+GitHub.sublime-settings
+
+### Vim ###
+[._]*.s[a-v][a-z]
+[._]*.sw[a-p]
+[._]s[a-v][a-z]
+[._]sw[a-p]
+Session.vim
+.netrwhist
+tags
+
+### VisualStudioCode ###
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+
+### Windows ###
+Thumbs.db
+ehthumbs.db
+ehthumbs_vista.db
+Desktop.ini
+$RECYCLE.BIN/

CMakeLists.txt

@@ -15,6 +15,14 @@
 cmake_minimum_required(VERSION 2.8)
 project(nxt C CXX)
 
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
+    message(FATAL_ERROR
+        "In-source builds are unsupported. Use another directory, like build/, "
+        "as your CMake build directory.\n"
+        "Note: CMakeFiles/ and CMakeCache.txt may have been generated in the "
+        "source directory. These may be removed.")
+endif()
+
 if(NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE "Debug" CACHE STRING
         "Build type (Debug, Release, RelWithDebInfo, MinSizeRel)" FORCE)