don't scan for .libPaths() changes while debugging
don't Step Into functions run by RStudio itself
protect additional vulnerable executions with DisableStepInto
don't restore browser command after debugging ends
use RDEBUG flag on global environment instead of R_BrowserLastCommand
save/restore debug flag on non-global environments
check for non-empty context stack before restoring debugging
fix clipboard copy in IE10+: cancel copy event when ACE copies manually
Improvements to C/C++ Indentation

This adds a large set of improvements to the C/C++ indentation modes for
RStudio. A variety of heuristics are used to infer the appropriate
indentation, and we now gain a number of useful bits:

1. Vertical alignment for function arguments,
2. Automatic namespace comments for close,
3. Smart indentation / outdent for braces, 'public:', and so on,
4. Smart indentation for constructors / initialization lists,