Support delta along with ANSI support (continuation)

[pablospe]

The original pull request was closed due to the author deleting their account.

Original PR description

#542 (comment)

• All test passes.
• I haven't seen segmentation faults with newest versions of MacOS Big Sur, iTerm2, and delta. ncurses version is 6.2.
• It looks like no performance issues.
• I've only tested it with Terminal.app and iTerm on MacOS.

how to use delta in tig?

It requires ncurse 6.1 or higher.

# if you don't have ncurses
curl -O ftp://ftp.gnu.org/gnu/ncurses/ncurses-6.2.tar.gz
tar -xzvf ncurses-6.2.tar.gz
cd ncurses-6.2
./configure --prefix=${where you like} --enable-pc-files --with-pkg-config-libdir=/usr/local/bin/pkgconfig --enable-sigwinch --enable-symlinks --enable-widec --with-shared --with-gpm=no --without-ada --enable-ext-colors # i set the path as /usr/local which is default
sudo make
sudo make install

cd ${path to tig of the branch of above PR}
make configure
./configure LDFLAGS=-L${where you download ncurses}/lib CPPFLAGS=-I{where you installed ncurses}/include  # i set the path as /usr/local/opt/ncurses which is installed by ncurses
make

echo "set diff-highlight = \"delta\"" >> ~/.tigrc

./src/tig

Note: a more detailed installation instructions can be found in this comment from @adamency.