Don't try to remove autodetected DLLs

[HebaruSan]

Problem

ckan remove --all currently tries to remove autodetected DLLs, which fails. This makes this command unusable on Steam installs, which always have two extra DLLs, KSPSteamCtrlr and Steamworks.

ckan remove --re regularexpression has the same problem if the regular expressions match any autodetected DLL.

Cause

Cmdline/Action/Remove.cs loops over Registry.Installed, which includes autodetected DLLs:

Installed: KSPSteamCtrlr autodetected dll
Installed: Steamworks autodetected dll
Installed: StockVisualEnhancements 3:1.2.7.0
Installed: SVE-LowResolution 3:1.0.2
Installed: Scatterer-sunflare 2:v0.0320b
Installed: Scatterer-config 2:v0.0320b
Installed: DistantObject-default v1.9.1
Installed: Scatterer 2:v0.0320b
Installed: EnvironmentalVisualEnhancements 2:EVE-1.2.2-1
Installed: ModuleManager 3.0.1
Installed: DistantObject v1.9.1

Changes

Now it uses Registry.InstalledModules, which does not include autodetected DLLs:

InstalledModule: StockVisualEnhancements 3:1.2.7.0
InstalledModule: SVE-LowResolution 3:1.0.2
InstalledModule: Scatterer-sunflare 2:v0.0320b
InstalledModule: Scatterer-config 2:v0.0320b
InstalledModule: DistantObject-default v1.9.1
InstalledModule: Scatterer 2:v0.0320b
InstalledModule: EnvironmentalVisualEnhancements 2:EVE-1.2.2-1
InstalledModule: ModuleManager 3.0.1
InstalledModule: DistantObject v1.9.1

Before

$ mono ckan.exe remove --all
I can't do that, KSPSteamCtrlr isn't installed.
Try `ckan list` for a list of installed mods.

After

$ mono ckan.exe remove --all
About to remove:

 * Stock Visual Enhancements 3:1.2.7.0
 * Stock Visual Enhancements-Low Resolution Textures 3:1.0.2
 * scatterer - sunflare 2:v0.0320b
 * scatterer - default config 2:v0.0320b
 * Distant Object Enhancement default config v1.9.1
 * scatterer 2:v0.0320b
 * Environmental Visual Enhancements 2:EVE-1.2.2-1
 * Module Manager 3.0.1
 * Distant Object Enhancement v1.9.1

Continue? [Y/n] 

Linkages

Fixes #1553.