fix logging-kernel/Holmakefile

(it should just be the same as experimental-kernel's, which changed
recently)
fix read_buildsequence for kernelnames

the comment in build-sequence says the kernel names are "otknl",
"stdknl" and "expk", but in the code they have a hyphen at the front. I
guess this isn't used for anything apart from otknl so hadn't been
tested much.
move opentheory earlier in build sequence

it is not a large theory - indeed there are no theories in these
directories, just some libraries, so take very little time to process.
update opentheory/logging/Holmakefile

for Holmake's new behaviour that does not automatically process all
*.sml by default
remove miniML from the gitignore file
move opentheory after string

since it depends on it. don't know why travis didn't catch this.