move loading of debugger to DebugTarget
don't allow starting multiple debuggers on the same node
run initialCall only on managed backends
dispose backends only once
create debugger.otp projects for each supported version
fix feature descriptions
make code loading from plugins respect code context and version
Revert "comment out code using named funs; revert when compiling with r17"

This reverts commit 39ab8f8d392af062fb80c319376bcb5fa410d889.
remove accidental non-breaking spaces
remove unused code
update jenkins tooling for otp 17
moved builder:load/2 to erlide_util, as it's generic
debugger: fix setting variable values
add script to allow applying patch to all debugger versions
debugger: update stacktrace handling
debugger: fix set_variable to only work at the top stackframe
debugger: update to latest from r17
debugger: apply erlide patches
debugger: update debugger code for r15 and r16
Merge branch 'debugger' into pu