Use gender-neutral pronouns when referring to the player

Closes #2783, #2784, #2751, #2749, #2734, #2704, #2360, and #2135

See merge request xonotic/xonotic-data.pk3dir!1111

diff --cc qcsrc/common/gamemodes/gamemode/ctf/sv_ctf.qc
Simple merge

diff --cc qcsrc/common/gamemodes/gamemode/lms/sv_lms.qc
Simple merge