x11.c: Use DISPLAY environment variable explicitly

Instead of relying on XOpenDisplay() to resolve the DISPLAY environment
variable, we retrieve it ourselves and pass it to the function.  This makes
the error handling code prettier.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Add bash submodule

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Automated indentation fixes (clang-format)

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Integrate bash into the terminal

This is surely the craziest thing I will do in years.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Update bash submodule, now including .gitignore

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Run internal bash through execve

This makes O_CLOEXEC flags effective, and gets rid of redundant page table
entries in the bash process.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Add preview of bash' "cd" command

This is the first use of the bash integration.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>
Move bash submodule hosting

Since I'm forking bash, I need separate hosting.

Signed-off-by: Morten Hustveit <morten.hustveit@gmail.com>