Fixed Start() hierarchy. More fixing of AeroFX

- Added virtual keyword to ModuleAeroReentry.Start()
- Added override keyword to ModuleHeatShield.Start()
- Fixed FixAeroFX() fixes. (was not properly calling coroutine)
- Moved crew/chute warning messages to ReentryPhysics
Moved config files

- ModuleManager 2.5.3 compatibility change: Moved difficulty and
settings related files to DeadlyReentry/Plugins/PluginData (Easy.cfg,
Default.cfg, Hard.cfg and Custom.cfg)
Hotfix reversion of config file move

- Reverted moving of difficulty settings files to PluginData. (cfg files
are not read from PluginData nor is GameDatabase able to see that folder
at all)
Menu Version updated

- Updated version number displayed on menus.
KSP 0.90 update (DRE beta 6.3.* to DRE 6.4.0)

*Added toolbar button (for stock toolbar)
*Added Easy, Normal and Hard difficulty settings accessible from new
menu
*Difficulty settings are per-save game!!! Use Easy for sandbox and Hard
for Career! (if you want)
*Alternate lower density calculation (for use with Hard mode to prevent
excessive heating for high speed aircraft)
*Fix for stuttering AeroFX cases. (thanks to Motokid600, Chezburgar7300,
Zeenobit and Noio for feedback and/or testing)
*Reworked warning messages for visibility and/or optimization
*Optimized density calculations (moved all into ReentryPhysics; no more
per-part calculations)
*Lowered part max-temperature cap to 1250 (other parts may be even
lower)
*Heat shields now insulate attached parts against conducted heat
*Low grade heat shielding added to nose cones and fairings. (also to
parachute 'cone' parts. Deploying chutes 'jettisons' the shield)
*Kerbals now react to reentry events such as overheating. (may need
tweaking; even Jebediah gets scared now. Can't have that)
*Merged in fixes from NathanKell for FAR detection
*Merged in changes from NathanKell to support R&D / Technology
requirements
*Added support for (currently unused)stock KSP airstream shielding
*Trapping and checking for of null reference errors in events.
*Added DeadlyReentry.version for AVC and CKAN support
Added logging of 64bit client detection.

Added logging of 64bit client detection.
Avoid problems in toolbar startup.

The correct thing to do is detect when the exception might happen and avoid
it, not try to catch it.
Add a toggle for the parachute warning.

It defaults to on since this is a useful feature for people new to DRE,
but it is most annoying for veterans.
Plug an NRE hole.

And remove the superfluous try/catch block. Having the correct Event
name helps.
Fix a typo.

s/unsave/unsafe/
Remove an unnecessary null check.

If OnSave is called, Instance cannot be null because it is guaranteed that
Awake will have been called.
Move the chute warning flag to the scenario.

This makes the setting "global" (ie for all difficulty settings) and
actually save properly without needing to hack the config files. It also
has the effect of making the setting per-save, which I consider to be a
good thing as it will serve as a reminder.
Visually separate the chute toggle from the other settings.

This makes it clear that the chute warning toggle is not part of the
difficulty settings.
Merge pull request #5 from taniwha-qf/master

NRE fixes and chute warning toggle.
Removed incorrect engine handling in FixMaxTemps

Removed incorrect engine handling in FixMaxTemps. (changing maxTemp that
way resulted in other parts not being handled)
Heatshields for Mk3 parts added

Heatshields for Mk3 parts added
Merging master changes to AltDissipation

Merging master changes to AltDissipation