Create EditorConfig file

Most files in this repo assume that tabs are 8 characters wide and use 2
spaces for indentation. Most people’s editors aren’t configured to do
that by default. This can lead to indentation mistakes [1].

The main motivation behind this change is to make indentation mistakes
less likely. Many editors [2] will automatically use whatever
indentation settings are in the EditorConfig file.


On an unrelated note, the EditorConfig that this commit adds includes a
tab_width property. This comment in cfile/cfile.h was the inspiration
for specifying the tab_width property:

// Opens a HOG file.  Future calls to cfopen(), etc. will look in this HOG.
// Parameters:  libname - the path & filename of the HOG file
// NOTE:	libname must be valid for the entire execution of the program.  Therefore, it should either
//			be a fully-specified path name, or the current directory must not change.
// Returns: 0 if error, else library handle that can be used to close the library
int cf_OpenLibrary(const char *libname);

When tab_width is set to 8, the first “libname” lines up with the second
“libname”, and the m in “must” lines up with the b in “be”. When
tab_width is set to its default value (4 in this case [3]), the first
“libname” doesn’t line up with anything, and the second “libname” lines
up with the b in “be”. It just looks more correct when tab_width is set
to 8.

[1]: <https://github.com/DescentDevelopers/Descent3/pull/372#issuecomment-2122445826>
[2]: <https://editorconfig.org/#pre-installed>
[3]: <https://spec.editorconfig.org/#supported-pairs>

.editorconfig

@@ -0,0 +1,21 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+tab_width = 8
+end_of_line = lf
+spelling_language = en-US
+
+[*.md]
+# I would use 2 spaces for indentation in Markdown files in order to be
+# consistent wit the rest of the project, but the GitHub Flavored Markdown Spec
+# requires that you use at least 4 spaces in certain situations:
+# <https://github.github.com/gfm/#indented-code-blocks>
+indent_size = 4
+
+# This end_of_line override exists in order to be consistent with
+# .gitattributes. If you add another override here, then you please also add it
+# to .gitattributes.
+[{*.vcproj,*.vcxproj}]
+end_of_line = crlf

.gitattributes

@@ -32,6 +32,8 @@
 *.yaml text eol=lf
 *.yml text eol=lf
 
+# .editorconfig also contains a list of files that should use CRLFs. If you add
+# a new “eol=crlf” here, then please also add it to .editorconfig.
 # Visual Studio project files
 *.vcproj text eol=crlf
 *.vcxproj text eol=crlf