Enable use of newer compiler version

[juntuu]

This could:

1. allow compiling with gcc 10.2, accompishing the same as Add workaround for compile error on stricter C++ compilers #164
2. allow for compiler upgrade to clang 11 / gcc 10
3. point 2 would enable c++17 features and Fix handling of .. in jepath() (requires <filesystem> header) #170 would compile

Tested with the following compiler versions on osx:

; /usr/local/Cellar/gcc/10.2.0_4/bin/gcc-10 --version
gcc-10 (Homebrew GCC 10.2.0_4) 10.2.0
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

; clang --version
Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: x86_64-apple-darwin20.3.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

[herwinw]

Just tested this, it fixes the problems I previously encountered, and this fix doesn't require stupid wrapper functions in C around every conflicting call.

/me approves