Add the needsterminal flag for the default mailcap entry.

it's used to pass the client certificate to the net process so has to be enabled. Issue <https://github.com/telescope-browser/telescope/issues/21> spotted by linuxcult; thank you!

Under certain conditions, set PKG_PATH_CONFIG programatically, as in, find all the relevant occurances under /opt/homebrew This is necessary because some CI systems might not do this, and it's a pain having to enumerate dependencies of dependencies. There is a slight downside that ./configure might pause for a few seconds.

Fix incorrect case for platform.

We should probably instead introduce the concept of ``target column'' but for now this brings back the behaviour pre-point_offset introduction, even if it gets it wrong when tabulator characters are involved.

tab characters have their width depending on the column they're in, since they extend to the next multiple of 8. (citation needed?) So, keep track of the column when considering the length (in columns) of the text, so that we can render them properly. In the future we might want to turn them into spaces (either at read or render time) just to stay on the safe side in case not all terminals/ncurses implementations use 8 columns.

we need to send a file descriptor to the net process when we use a custom client certificate. Don't know how I missed it...

since we can't move the cursor past the last column, we can't draw a character there.

libgrapheme does a few more checks than we do