Update .gitignore and add .gitattributes

.gitattributes is a portable solution to normalize line endings when working cross-platform

.gitattributes

@@ -0,0 +1,12 @@
+*.py text eol=lf
+*.yml text eol=lf
+*.diff text eol=lf
+*.conf text eol=lf
+*.md text eol=lf
+*.cc text eol=lf
+*.hh text eol=lf
+*.txt text eol=lf
+*.build text eol=lf 
+*.gitattributes text eol=lf 
+*.gitignores text eol=lf 
+*.wrap text eol=lf 

.gitignore

@@ -2,3 +2,6 @@ subprojects/libostd
 *.o
 *.core
 *.so
+build/
+.idea/
+.vscode/