Use optimized kotlin grammar

[dolik-rce]

I have been developing pegof as a hobby project for past few years. Recently it became good enough to optimize Kotlin grammar, making it 3 times faster and about 2.7 times less memory hungry.

With this PR, I'd like to start a discussion on how to best use this improvement in ctags. I'd like to keep the original, "human readable" version of the grammar in the repo to ensure simple updates and readable git history. On the other hand, I don't think it would be good idea to make ctags build to depend on pegof, it is not available on all platforms. So my proposal is to allow only manual optimization and keep both original and optimized grammar in the repository. What do you think?

---

Here is a simple benchmark using ctags-codebase to prove that it really makes a difference:

echo "# optimized"
git checkout optimized-kotlin-peg &> /dev/null
make ctags > /dev/null
/usr/bin/time -f "time: %E\nmax memory (kb): %M" ./ctags -f optimized.ctags ../ctags-codebase/code/kotlin/libraries/**/*.kt

echo "# master"
git checkout master &> /dev/null
make ctags > /dev/null
/usr/bin/time -f "time: %E\nmax memory (kb): %M" ./ctags -f master.ctags ../ctags-codebase/code/kotlin/libraries/**/*.kt

echo "# output comparison"
diff optimized.ctags master.ctags
wc -l optimized.ctags master.ctags 

Output:

# optimized
time: 0:13.84
max memory (kb): 447792
# master
time: 0:44.18
max memory (kb): 1204216
# output comparison
31c31
< !_TAG_PROGRAM_VERSION 6.1.0   /885afcb3e/
---
> !_TAG_PROGRAM_VERSION 6.1.0   /8976ec3d2/
   92478 optimized.ctags
   92478 master.ctags
  184956 total