Use K_TRIM getstr() mode when prompting for filenames

Don't need no stinking pre/appended white-space in our filenames!
14 jobs for dailybuild_linux-x64 in 9 minutes and 12 seconds (queued for 14 seconds)
Status Job ID Name Coverage
  Build
passed #25784
FreeBSD
jsdoor-freebsd

00:05:26

passed #25785
Linux
jsdoor-linux

00:05:06

passed #25787
FreeBSD
jsdoor-windows

00:02:52

passed #25779
FreeBSD
sbbs-freebsd

00:07:35

passed #25774
Linux
sbbs-linux

00:09:06

passed #25777
Windows
sbbs-windows

00:05:19

passed #25786
FreeBSD
sexpots-freebsd

00:00:12

passed #25775
Linux
sexpots-linux

00:00:13

passed #25778
Windows
sexpots-windows

00:00:26

passed #25782
FreeBSD
syncdraw-freebsd

00:00:30

passed #25783
Linux
syncdraw-linux

00:01:04

passed #25780
FreeBSD
syncterm-freebsd

00:01:23

passed #25776
Linux
syncterm-linux

00:02:41

passed #25781
FreeBSD
syncterm-windows

00:02:39