Fix for keypad enter issue

Don't tell the system to disable compositing under X11

Fixes #123

The value should not be updated if the current first_invalid_line is less than
the new invalid line index

the current-working-directory is now set at the start of `core.init` after the
absolute path for all filename arguments have been resolved

As the window isn't created until the first frame is drawn this is required to
assure the window is ever shown without relying on the assumption that some
other part of the program would have set this to true

Enable LUA_USE_POSIX, fix tmpnam warning on macOS.

Fixes #63

On macOS, we want to use `mkstemp` rather than `tmpnam`. Enable
POSIX support in Lua to fix that (and some other things). Since
POSIX support also enables the flag for POPEN, we no longer need
to do that directly for Linux.

Resolves #109

Fixes #100

Filenames that match either the single pattern provided by
`config.ignore_files`, or any pattern in a table of patterns, will be ignored
when lite is filling the `core.project_files` table

Resolves #77
Resolves #102

Fixed various issues in exec:replace

Fixes #97

This, along with the earlier rencache changes should resolve #64