tkdiff Code

* The NewDiff interactive Dialog is now the default when no args given
- it permits a simpler startup on graphical desktops via shortcuts
- yet still allows dynamic searching for SCM-based diff candidates, and
- its controls are now inter-related to assist making correct settings
* Users may now specify a preferred SCM system among those detectable
* Additionally, the SCM system may be manually selected during dialog use
* A new autoSrch preference allows immediate SCM startup from the cmdline
* It is now possible to COMBINE usage of two distinct SCMs, if desired;
- this also facilitates comparisons between distinct branches of an SCM
* It is now possible to request a "conflict" diff via the dialog
* Conflict parsing now accepts a diff3-like format (but only as a 2way)
* The (internal) setting of prefs is now managed to prevent lost settings
* Resolved a race condition causing instability in redrawing the DiffMap
* More uniformity of error messaging - particularly fatal errors
* New Help info on the role of the CWD during tool startup, plus the SCM
- features, and interpreting the interactive feedback from the dialog

Add inquire-cvs proc so tkdiff with no arguments queries cvs for modified files to load, like git and svn

* Added ability to recognize 3way mode is active and view the Ancestor file
* Builtin editor now provides Line numbers for displayed files

Provide clear feedback when a three-way merge is in effect

Fix minor graphic feedback artifacts (particularly w/zero hunks) when doing a new Diff

Repaired internal variable renaming oversight (1 instance)

Use is-git-repository instead of is-repo-dir in proc scm_detect, because presence of a .git directory is only one possibility

* Further improved newDiff dialog now permits browsing to an Ancestor file
- additionally it can be specified as a SCM revision instance, perhaps
- from distinct branches (presuming each WC knows the branch it represents)
* Now accepts entering 2 FileSpec + 2 Revisions where Filespecs are NOT the
- same allowing comparisons of distinct branches (for branch sensitive WCs)
* 3way collisions now highlight within the dropdown list (a location aid)
* The GUI txtwin labels now tooltip the REAL filename+modtimes (no tmpfils)
* MacOS X prevented from using ASYNC due to Aqua non-support for msg window
* Fixed missing usage of CDR-specific preferences within all Info displays
* Updated help on new input formats, 3way strategies, and PWD implications

* Improved newDiff dialog now permits browsing to Files OR Directories
- additionally it and browsers now stack above each other properly
- And now agrees w/help stating that "More" options UNSET when closed
* Repaired crash when Lnum/Chgbar are both OFF and 3way diff is/has run
* Map color pref chgs now WORK in the current session (besides 'save')
* All Info canvases now use 'currtag' prefs as intended (was ignoring)
* Transparent (internal) conversions to recent (Tcl8.5) coding techniques
- use of 'lassign' instead of 'foreach ... {}' hack
- use of 'apply' to manufacture anonymous event handler
- greater use of '{*}' list expansion style instead of 'eval'
* minor typos, safer internal constructs, consolidations, plus more uniformity

forgot to commit the Changelog